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The Denitive Guide to Yii 1.1
Qiang Xue and Xiang Wei Zhuo
Copyright 2008-2010.All Rights Reserved.
Contents
Contents i
License xi
1 Getting Started 1
1.1 The Denitive Guide to Yii...........................1
1.2 New Features...................................1
1.2.1 Version 1.1.3...............................1
1.2.2 Version 1.1.2...............................1
1.2.3 Version 1.1.1...............................1
1.2.4 Version 1.1.0...............................2
1.2.5 Version 1.0.11...............................2
1.2.6 Version 1.0.10...............................2
1.2.7 Version 1.0.8...............................2
1.2.8 Version 1.0.7...............................3
1.2.9 Version 1.0.6...............................3
1.2.10 Version 1.0.5...............................3
1.3 Upgrading from Version 1.0 to 1.1.......................4
1.3.1 Changes Related with Model Scenarios.................4
1.3.2 Changes Related with Eager Loading for Relational Active Record.4
1.3.3 Changes Related with Table Alias in Relational Active Record...5
ii Contents
1.3.4 Changes Related with Tabular Input..................5
1.3.5 Other Changes..............................5
1.4 What is Yii....................................5
1.4.1 Requirements...............................5
1.4.2 What is Yii Best for?..........................5
1.4.3 How is Yii Compared with Other Frameworks?............6
1.5 Installation....................................6
1.5.1 Requirements...............................6
1.6 Creating First Yii Application..........................7
1.6.1 Connecting to Database.........................11
1.6.2 Implementing CRUD Operations....................12
2 Fundamentals 17
2.1 Model-View-Controller (MVC).........................17
2.1.1 A Typical Workow...........................18
2.2 Entry Script....................................19
2.2.1 Debug Mode...............................19
2.3 Application....................................20
2.3.1 Application Conguration........................20
2.3.2 Application Base Directory.......................21
2.3.3 Application Component.........................21
2.3.4 Core Application Components.....................22
2.3.5 Application Lifecycles..........................23
2.4 Controller.....................................24
2.4.1 Route...................................24
Contents iii
2.4.2 Controller Instantiation.........................25
2.4.3 Action...................................25
2.4.4 Filter...................................26
2.5 Model.......................................28
2.6 View........................................29
2.6.1 Layout...................................29
2.6.2 Widget..................................30
2.6.3 System View...............................31
2.7 Component....................................31
2.7.1 Component Property...........................31
2.7.2 Component Event............................32
2.7.3 Component Behavior...........................33
2.8 Module......................................35
2.8.1 Creating Module.............................35
2.8.2 Using Module...............................36
2.8.3 Nested Module..............................37
2.9 Path Alias and Namespace...........................37
2.10 Conventions....................................39
2.10.1 URL....................................39
2.10.2 Code....................................39
2.10.3 Conguration...............................40
2.10.4 File....................................40
2.10.5 Directory.................................40
2.10.6 Database.................................41
iv Contents
2.11 Development Workow..............................42
3 Working with Forms 45
3.1 Working with Form................................45
3.2 Creating Model..................................45
3.2.1 Dening Model Class...........................46
3.2.2 Declaring Validation Rules.......................46
3.2.3 Securing Attribute Assignments.....................49
3.2.4 Triggering Validation...........................52
3.2.5 Retrieving Validation Errors......................53
3.2.6 Attribute Labels.............................53
3.3 Creating Action..................................53
3.4 Creating Form..................................55
3.5 Collecting Tabular Input.............................57
3.6 Using Form Builder...............................58
3.6.1 Basic Concepts..............................59
3.6.2 Creating a Simple Form.........................59
3.6.3 Specifying Form Elements........................61
3.6.4 Accessing Form Elements........................64
3.6.5 Creating a Nested Form.........................65
3.6.6 Customizing Form Display.......................67
4 Working with Databases 69
4.1 Working with Database.............................69
4.2 Data Access Objects (DAO)...........................69
Contents v
4.2.1 Establishing Database Connection...................70
4.2.2 Executing SQL Statements.......................71
4.2.3 Fetching Query Results.........................72
4.2.4 Using Transactions............................72
4.2.5 Binding Parameters...........................73
4.2.6 Binding Columns.............................74
4.2.7 Using Table Prex............................74
4.3 Active Record...................................74
4.3.1 Establishing DB Connection.......................75
4.3.2 Dening AR Class............................76
4.3.3 Creating Record.............................78
4.3.4 Reading Record..............................79
4.3.5 Updating Record.............................82
4.3.6 Deleting Record.............................82
4.3.7 Data Validation..............................83
4.3.8 Comparing Records...........................84
4.3.9 Customization..............................84
4.3.10 Using Transaction with AR.......................84
4.3.11 Named Scopes..............................85
4.4 Relational Active Record............................87
4.4.1 Declaring Relationship..........................88
4.4.2 Performing Relational Query......................90
4.4.3 Relational Query Options........................92
4.4.4 Disambiguating Column Names.....................94
vi Contents
4.4.5 Dynamic Relational Query Options...................94
4.4.6 Relational Query Performance.....................95
4.4.7 Statistical Query.............................96
4.4.8 Relational Query with Named Scopes.................98
5 Caching 101
5.1 Caching......................................101
5.2 Data Caching...................................103
5.2.1 Cache Dependency............................104
5.3 Fragment Caching................................105
5.3.1 Caching Options.............................105
5.3.2 Nested Caching..............................107
5.4 Page Caching...................................108
5.5 Dynamic Content.................................109
6 Extending Yii 111
6.1 Overview.....................................111
6.2 Using Extensions.................................112
6.2.1 Zii Extensions...............................112
6.2.2 Application Component.........................113
6.2.3 Behavior..................................113
6.2.4 Widget..................................114
6.2.5 Action...................................115
6.2.6 Filter...................................115
6.2.7 Controller.................................116
Contents vii
6.2.8 Validator.................................116
6.2.9 Console Command............................117
6.2.10 Module..................................117
6.2.11 Generic Component...........................117
6.3 Creating Extensions...............................118
6.3.1 Application Component.........................118
6.3.2 Behavior..................................119
6.3.3 Widget..................................119
6.3.4 Action...................................121
6.3.5 Filter...................................121
6.3.6 Controller.................................121
6.3.7 Validator.................................122
6.3.8 Console Command............................122
6.3.9 Module..................................122
6.3.10 Generic Component...........................123
6.4 Using 3rd-Party Libraries............................123
7 Testing 125
7.1 Overview.....................................125
7.2 Test-Driven Development............................126
7.3 Test Environment Setup.............................126
7.4 Test Bootstrap Script..............................127
7.5 Dening Fixtures.................................128
7.6 Unit Testing....................................130
7.7 Functional Testing................................132
viii Contents
8 Special Topics 135
8.1 Automatic Code Generation...........................135
8.1.1 Using Gii.................................135
8.1.2 Extending Gii...............................137
8.2 URL Management................................143
8.2.1 Creating URLs..............................143
8.2.2 User-friendly URLs............................144
8.3 Authentication and Authorization.......................149
8.3.1 Dening Identity Class..........................149
8.3.2 Login and Logout............................151
8.3.3 Access Control Filter...........................151
8.3.4 Role-Based Access Control.......................154
8.4 Theming......................................160
8.4.1 Customizing Widgets Globally.....................162
8.4.2 Skin....................................163
8.5 Logging......................................166
8.5.1 Message Logging.............................166
8.5.2 Message Routing.............................167
8.5.3 Performance Proling..........................169
8.6 Error Handling..................................170
8.6.1 Raising Exceptions............................171
8.6.2 Displaying Errors.............................171
8.6.3 Message Logging.............................173
8.7 Web Service....................................173
Contents ix
8.7.1 Dening Service Provider........................174
8.7.2 Declaring Web Service Action......................175
8.7.3 Consuming Web Service.........................175
8.7.4 Data Types................................176
8.7.5 Class Mapping..............................177
8.7.6 Intercepting Remote Method Invocation................178
8.8 Internationalization................................178
8.8.1 Locale and Language...........................178
8.8.2 Translation................................179
8.8.3 Date and Time Formatting.......................182
8.8.4 Number Formatting...........................183
8.9 Using Alternative Template Syntax.......................183
8.9.1 Using CPradoViewRenderer........................184
8.9.2 Mixing Template Formats........................187
8.10 Console Applications...............................187
8.10.1 Using the yiic Tool...........................188
8.11 Security......................................189
8.11.1 Cross-site Scripting Prevention.....................189
8.11.2 Cross-site Request Forgery Prevention.................189
8.11.3 Cookie Attack Prevention........................190
8.12 Performance Tuning...............................191
8.12.1 Enabling APC Extension........................191
8.12.2 Disabling Debug Mode..........................192
8.12.3 Using yiilite.php............................192
x Contents
8.12.4 Using Caching Techniques........................192
8.12.5 Database Optimization.........................193
8.12.6 Minimizing Script Files.........................193
8.13 Code Generation using Command Line Tools (deprecated)..........195
License of Yii
The Yii framework is free software.It is released under the terms of the following BSD
License.
Copyright
c
2008-2010 by Yii Software LLC.All rights reserved.
Redistribution and use in source and binary forms,with or without modication,are
permitted provided that the following conditions are met:
1.Redistributions of source code must retain the above copyright notice,this list of
conditions and the following disclaimer.
2.Redistributions in binary formmust reproduce the above copyright notice,this list of
conditions and the following disclaimer in the documentation and/or other materials
provided with the distribution.
3.Neither the name of Yii Software LLC nor the names of its contributors may be
used to endorse or promote products derived from this software without specic
prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS"AS
IS"AND ANY EXPRESS OR IMPLIED WARRANTIES,INCLUDING,BUT NOT LIMITED TO,THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PUR-
POSE ARE DISCLAIMED.IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBU-
TORS BE LIABLE FOR ANY DIRECT,INDIRECT,INCIDENTAL,SPECIAL,EXEMPLARY,OR
CONSEQUENTIAL DAMAGES (INCLUDING,BUT NOT LIMITED TO,PROCUREMENT OF SUB-
STITUTE GOODS OR SERVICES;LOSS OF USE,DATA,OR PROFITS;OR BUSINESS INTERRUP-
TION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,WHETHER IN CONTRACT,
STRICT LIABILITY,OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
WAY OUT OF THE USE OF THIS SOFTWARE,EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
xii Contents
Chapter 1
Getting Started
1.1 The Denitive Guide to Yii
This tutorial is released under the Terms of Yii Documentation.
All Rights Reserved.
2008-2010 copy;Yii Software LLC.
1.2 New Features
This page summarizes the main new features introduced in each Yii release.
1.2.1 Version 1.1.3
Added support to congure widget default values in application conguration
1.2.2 Version 1.1.2
Added a Web-based code generation tool called Gii
1.2.3 Version 1.1.1
Added CActiveForm which simplies writing form-related code and supports seam-
less and consistent validation on both client and server sides.
Refactored the code generated by the yiic tool.In particular,the skeleton applica-
tion is now generated with multiple layouts;the operation menu is reorganized for
CRUD pages;added search and ltering feature to the admin page generated by
crud command;used CActiveForm to render a form.
Added support to allow dening global yiic commands
2 1.Getting Started
1.2.4 Version 1.1.0
Added support for writing unit and functional tests
Added support for using widget skins
Added an extensible form builder
Improved the way of declaring safe model attributes.See Securing Attribute Assign-
ments.
Changed the default eager loading algorithm for relational active record queries so
that all tables are joined in one single SQL statement.
Changed the default table alias to be the name of active record relations.
Added support for using table prex.
Added a whole set of new extensions known as the Zii library.
The alias name for the primary table in an AR query is xed to be't'
1.2.5 Version 1.0.11
Added support for parsing and creating URLs with parameterized hostnames
{ Parameterizing Hostnames
1.2.6 Version 1.0.10
Enhanced support for using CPhpMessageSource to manage module messages
{ Message Translation
Added support for attaching anonymous functions as event handlers
{ Component Event
1.2.7 Version 1.0.8
Added support for retrieving multiple cached values at one time
{ Data Caching
Introduced a new default root path alias ext which points to the directory containing
all third-party extensions.
{ Using Extensions
1.2 New Features 3
1.2.8 Version 1.0.7
Added support for displaying call stack information in trace messages
{ Logging Context Information
Added index option to AR relations so that related objects can be indexed using the
values of a specic column
{ Relational Query Options
1.2.9 Version 1.0.6
Added support for using named scope with update and delete methods:
{ Named Scopes
Added support for using named scope in the with option of relational rules:
{ Relational Query with Named Scopes
Added support for proling SQL executions
{ Proling SQL Executions
Added support for logging additional context information
{ Logging Context Information
Added support for customizing a single URL rule by setting its urlFormat and cas-
eSensitive options:
{ User-friendly URLs
Added support for using a controller action to display application errors:
{ Handling Errors Using an Action
1.2.10 Version 1.0.5
Enhanced active record by supporting named scopes.See:
{ Named Scopes
{ Default Named Scope
4 1.Getting Started
{ Relational Query with Named Scopes
Enhanced active record by supporting lazy loading with dynamic query options.See:
{ Dynamic Relational Query Options
Enhanced CUrlManager to support parameterizing the route part in URL rules.See:
{ Parameterizing Routes in URL Rules
1.3 Upgrading from Version 1.0 to 1.1
1.3.1 Changes Related with Model Scenarios
Removed CModel::safeAttributes().Safe attributes are now dened to be those that
are being validated by some rules as dened in CModel::rules() for the particular
scenario.
Changed CModel::validate(),CModel::beforeValidate() and CModel::afterValidate().
CModel::setAttributes(),CModel::getSafeAttributeNames() The'scenario'parame-
ter is removed.You should get and set the model scenario via CModel::scenario.
Changed CModel::getValidators() and removed CModel::getValidatorsForAttribute().
CModel::getValidators() now only returns validators applicable to the scenario as
specied by the model's scenario property.
Changed CModel::isAttributeRequired() and CModel::getValidatorsForAttribute().
The scenario parameter is removed.The model's scenario property will be used,
instead.
Removed CHtml::scenario.CHtml will use the model's scenario property instead.
1.3.2 Changes Related with Eager Loading for Relational Active Record
By default,a single JOIN statement will be generated and executed for all relations
involved in the eager loading.If the primary table has its LIMIT or OFFSET query
option set,it will be queried alone rst,followed by another SQL statement that
brings back all its related objects.Previsoulay in version 1.0.x,the default behavior
is that there will be N+1 SQL statements if an eager loading involves N HAS
MANY or
MANY
MANY relations.
1.4 What is Yii 5
1.3.3 Changes Related with Table Alias in Relational Active Record
The default alias for a relational table is now the same as the corresponding relation
name.Previously in version 1.0.x,by default Yii would automatically generate a
table alias for each relational table,and we had to use the prex??.to refer to this
automatically generated alias.
The alias name for the primary table in an AR query is xed to be t.Previsouly in
version 1.0.x,it was the same as the table name.This will cause existing AR query
code to break if they explicity specify column prexes using the table name.The
solution is to replace these prexes with't.'.
1.3.4 Changes Related with Tabular Input
For attribute names,using Field[$i] is not valid anymore,they should look like
[$i]Field in order to support array-typed elds (e.g.[$i]Field[$index]).
1.3.5 Other Changes
The signature of the CActiveRecord constructor is changed.The rst parameter
(list of attributes) is removed.
1.4 What is Yii
Yii is a high-performance component-based PHP framework for developing large-scale Web
applications rapidly.It enables maximum reusability in Web programming and can signif-
icantly accelerate your Web application development process.The name Yii (pronounced
as Yee or [ji:]) stands for easy,ecient and extensible.
1.4.1 Requirements
To run a Yii-powered Web application,you need a Web server supporting PHP 5.1.0 or
higher.
For developers who want to use Yii,understanding object-oriented programming (OOP)
is very helpful,because Yii is a pure OOP framework.
1.4.2 What is Yii Best for?
Yii is a generic Web programming framework that can be used for developing virtually all
sorts of Web applications.Because it is light-weighted and equipped with sophisticated
6 1.Getting Started
caching solutions,it is especially suitable for developing high-trac applications,such as
portals,forums,content management systems (CMS),e-commerce systems,etc.
1.4.3 How is Yii Compared with Other Frameworks?
Like most PHP frameworks,Yii is an MVC framework.
Yii excels over other PHP frameworks in that it is ecient,feature-rich and clearly-
documented.Yii is carefully designed fromthe beginning to t for serious Web application
development.It is neither a byproduct of some project nor a conglomerate of third-party
work.It is the result of the authors'rich experience of Web application development and
the investigation and reection of the most popular Web programming frameworks and
applications.
1.5 Installation
Installation of Yii mainly involves the following two steps:
1.Download Yii Framework from yiiframework.com.
2.Unpack the Yii release le to a Web-accessible directory.
Tip:Yii does not need to be installed under a Web-accessible directory.A Yii
application has one entry script which is usually the only le that needs to be
exposed to Web users.Other PHP scripts,including those from Yii,should be
protected from Web access since they may be exploited for hacking.
1.5.1 Requirements
After installing Yii,you may want to verify that your server satises all the requirements
of using Yii.You can do so by accessing the requirement checker script at the following
URL in a Web browser:
http://hostname/path/to/yii/requirements/index.php
The minimum requirement by Yii is that your Web server supports PHP 5.1.0 or above.
Yii has been tested with Apache HTTP server on Windows and Linux operating systems.
It may also run on other Web servers and platforms,provided PHP 5 is supported.
1.6 Creating First Yii Application 7
1.6 Creating First Yii Application
To get an initial experience with Yii,we describe in this section how to create our rst
Yii application.We will use the powerful yiic tool which can be used to automate code
creation for certain tasks.For convenience,we assume that YiiRoot is the directory where
Yii is installed,and WebRoot is the document root of our Web server.
Run yiic on the command line as follows:
% YiiRoot/framework/yiic webapp WebRoot/testdrive
Note:When running yiic on Mac OS,Linux or Unix,you may need to change the
permission of the yiic le so that it is executable.Alternatively,you may run the
tool as follows,
% cd WebRoot/testdrive
% php YiiRoot/framework/yiic.php webapp WebRoot/testdrive
This will create a skeleton Yii application under the directory WebRoot/testdrive.The
application has a directory structure that is is needed by most Yii applications.
Without writing a single line of code,we can test drive our rst Yii application by accessing
the following URL in a Web browser:
http://hostname/testdrive/index.php
As we can see,the application has four pages:the homepage,the about page,the contact
page and the login page.The contact page displays a contact form that users can ll in to
submit their inquiries to the webmaster,and the login page allows users to be authenticated
before accessing privileged contents.See the following screenshots for more details.
The following diagram shows the directory structure of our application.Please see Con-
ventions for detailed explanation about this structure.
testdrive/
index.php Web application entry script file
index-test.php entry script file for the functional tests
assets/containing published resource files
css/containing CSS files
images/containing image files
themes/containing application themes
8 1.Getting Started
Figure 1.1:Home page
Figure 1.2:Contact page
1.6 Creating First Yii Application 9
Figure 1.3:Contact page with input errors
Figure 1.4:Contact page with success
10 1.Getting Started
Figure 1.5:Login page
protected/containing protected application files
yiic yiic command line script for Unix/Linux
yiic.bat yiic command line script for Windows
yiic.php yiic command line PHP script
commands/containing customized'yiic'commands
shell/containing customized'yiic shell'commands
components/containing reusable user components
Controller.php the base class for all controller classes
Identity.php the'Identity'class used for authentication
config/containing configuration files
console.php the console application configuration
main.php the Web application configuration
test.php the configuration for the functional tests
controllers/containing controller class files
SiteController.php the default controller class
data/containing the sample database
schema.mysql.sql the DB schema for the sample MySQL database
schema.sqlite.sql the DB schema for the sample SQLite database
testdrive.db the sample SQLite database file
extensions/containing third-party extensions
messages/containing translated messages
models/containing model class files
LoginForm.php the form model for'login'action
ContactForm.php the form model for'contact'action
runtime/containing temporarily generated files
tests/containing test scripts
views/containing controller view and layout files
layouts/containing layout view files
1.6 Creating First Yii Application 11
main.php the base layout shared by all pages
column1.php the layout for pages using a single column
column2.php the layout for pages using two columns
site/containing view files for the'site'controller
pages/containing"static"pages
about.php the view for the"about"page
contact.php the view for'contact'action
error.php the view for'error'action (displaying external errors)
index.php the view for'index'action
login.php the view for'login'action
1.6.1 Connecting to Database
Most Web applications are backed by databases.Our test-drive application is not an
exception.To use a database,we need to tell the application how to connect to it.This is
done in the application conguration le WebRoot/testdrive/protected/config/main.php,
highlighted as follows,
return array(
......
'components'=>array(
......
'db'=>array(
'connectionString'=>'sqlite:protected/data/testdrive.db',
),
),
......
);
The above code instructs Yii that the application should connect to the SQLite database
WebRoot/testdrive/protected/data/testdrive.db when needed.Note that the SQLite
database is already included in the skeleton application that we just generated.The
database contains only a single table named tbl
user:
CREATE TABLE tbl
user (
id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
username VARCHAR(128) NOT NULL,
password VARCHAR(128) NOT NULL,
email VARCHAR(128) NOT NULL
);
If you want to try a MySQL database instead,you may use the included MySQL schema
le WebRoot/testdrive/protected/data/schema.mysql.sql to create the database.
12 1.Getting Started
Note:To use Yii's database feature,we need to enable PHP PDO extension and
the driver-specic PDO extension.For the test-drive application,we need to turn
on both the php
pdo and php
pdo
sqlite extensions.
1.6.2 Implementing CRUD Operations
Now is the fun part.We would like to implement the CRUD (create,read,update and
delete) operations for the User table we just created.This is also commonly needed in
practical applications.Instead of taking the trouble to write the actual code,we will use
Gii { a powerful Web-based code generator.
Info:Gii has been available since version 1.1.2.Before that,we can use the afore-
mentioned yiic tool to accomplish the same goal.For more details,please refer to
Implementing CRUD Operations with yiic shell.
Conguring Gii
In order to use Gii,we rst need to edit the le WebRoot/testdrive/protected/config/
main.php,which is known as the application conguration le:
return array(
......
'import'=>array(
'application.models.*',
'application.components.*',
),
'modules'=>array(
'gii'=>array(
'class'=>'system.gii.GiiModule',
'password'=>'pick up a password here',
),
),
);
Then,visit the URL http://hostname/testdrive/index.php?r=gii.We will be prompted
for a password,which should be the one that we just entered in the above application
conguration.
1.6 Creating First Yii Application 13
Generating User Model
After login,click on the link Model Generator.This will bring us to the following model
generation page,
Figure 1.6:Model Generator
In the Table Name eld,enter tbl
user.In the Model Class eld,enter User.Then press
the Preview button.This will show us the new code le to be generated.Now press the
Generate button.A new le named User.php will be generated under protected/models.
As we will describe later in this guide,this User model class allows us to talk to the
underlying database tbl
user table in an object-oriented fashion.
Generating CRUD Code
After creating the model class le,we will generate the code that implements the CRUD
operations about the user data.We choose the Crud Generator in Gii,shown as follows,
In the Model Class eld,enter User.In the Controller ID eld,enter user (in lower case).
Now press the Preview button followed by the Generate button.We are done with the
CRUD code generation.
Accessing CRUD Pages
Let's enjoy our work by browsing the following URL:
14 1.Getting Started
Figure 1.7:CRUD Generator
http://hostname/testdrive/index.php?r=user
This will display a list of user entries in the tbl
user table.
Click the Create User button on the page.We will be brought to the login page if we have
not logged in before.After logged in,we see an input form that allows us to add a new
user entry.Complete the form and click on the Create button.If there is any input error,
a nice error prompt will show up which prevents us from saving the input.Back to the
user list page,we should see the newly added user appearing in the list.
Repeat the above steps to add more users.Notice that user list page will automatically
paginate the user entries if there are too many to be displayed in one page.
If we login as an administrator using admin/admin,we can view the user admin page with
the following URL:
http://hostname/testdrive/index.php?r=user/admin
This will show us the user entries in a nice tabular format.We can click on the table
header cells to sort the corresponding columns.We can click on the buttons on each row
of data to view,update or delete the corresponding row of data.We can browse dierent
pages.We can also lter and search to look for the data we are interested in.
All these nice features come without requiring us to write a single line of code!
1.6 Creating First Yii Application 15
Figure 1.8:User admin page
16 1.Getting Started
Figure 1.9:Create new user page
Chapter 2
Fundamentals
2.1 Model-View-Controller (MVC)
Yii implements the model-view-controller (MVC) design pattern which is widely adopted in
Web programming.MVCaims to separate business logic fromuser interface considerations
so that developers can more easily change each part without aecting the other.In MVC,
the model represents the information (the data) and the business rules;the view contains
elements of the user interface such as text,form inputs;and the controller manages the
communication between the model and the view.
Besides MVC,Yii also introduces a front-controller,called application,which represents
the execution context of request processing.Application resolves the user request and
dispatches it to an appropriate controller for further handling.
The following diagram shows the static structure of a Yii application:
Figure 2.1:Static structure of Yii application
18 2.Fundamentals
2.1.1 A Typical Workow
The following diagram shows a typical workow of a Yii application when it is handling a
user request:
Figure 2.2:A typical workow of Yii application
1.A user makes a request with the URL http://www.example.com/index.php?r=post/
show&id=1 and the Web server handles the request by executing the bootstrap script
index.php.
2.The bootstrap script creates an application instance and runs it.
3.The application obtains the detailed user request information from an application
component named request.
4.The application determines the requested controller and action with the help of an
application component named urlManager.For this example,the controller is post
which refers to the PostController class;and the action is show whose actual meaning
is determined by the controller.
5.The application creates an instance of the requested controller to further handle the
user request.The controller determines that the action show refers to a method
2.2 Entry Script 19
named actionShow in the controller class.It then creates and executes lters (e.g.
access control,benchmarking) associated with this action.The action is executed if
it is allowed by the lters.
6.The action reads a Post model whose ID is 1 from the database.
7.The action renders a view named show with the Post model.
8.The view reads and displays the attributes of the Post model.
9.The view executes some widgets.
10.The view rendering result is embedded in a layout.
11.The action completes the view rendering and displays the result to the user.
2.2 Entry Script
Entry script is the bootstrap PHP script that handles user requests initially.It is the only
PHP script that end users can directly request to execute.
In most cases,entry script of a Yii application contains the code that is as simple as
follows,
//remove the following line when in production mode
defined('YII
DEBUG') or define('YII
DEBUG',true);
//include Yii bootstrap file
require
once('path/to/yii/framework/yii.php');
//create application instance and run
$configFile='path/to/config/file.php';
Yii::createWebApplication($configFile)->run();
The script rst includes the Yii framework bootstrap le yii.php.It then creates a Web
application instance with the specied conguration and runs it.
2.2.1 Debug Mode
A Yii application can run in either debug or production mode according to the constant
value YII
DEBUG.By default,this constant value is dened as false,meaning production
mode.To run in debug mode,dene this constant as true before including the yii.php le.
Running application in debug mode is less ecient because it keeps many internal logs.
On the other hand,debug mode is also more helpful during development stage because it
provides richer debugging information when error occurs.
20 2.Fundamentals
2.3 Application
Application represents the execution context of request processing.Its main task is to
resolve the user request and dispatch it to an appropriate controller for further processing.
It also serves as the central place for keeping application-level congurations.For this
reason,application is also called front-controller.
Application is created as a singleton by the entry script.The application singleton can be
accessed at any place via Yii::app().
2.3.1 Application Conguration
By default,application is an instance of CWebApplication.To customize it,we normally
provide a conguration le (or array) to initialize its property values when the application
instance is being created.An alternative way of customizing application is to extend
CWebApplication.
The conguration is an array of key-value pairs.Each key represents the name of a
property of the application instance,and each value the corresponding property's initial
value.For example,the following conguration congures the name and defaultController
properties of the application.
array(
'name'=>'Yii Framework',
'defaultController'=>'site',
)
We usually store the conguration in a separate PHP script (e.g.protected/config/main.
php).Inside the script,we return the conguration array as follows,
return array(...);
To apply the conguration,we pass the conguration le name as a parameter to the
application's constructor,or to Yii::createWebApplication() like the following,which is
usually done in the entry script:
$app=Yii::createWebApplication($configFile);
2.3 Application 21
Tip:If the application conguration is very complex,we can split it into several les,
each returning a portion of the conguration array.Then,in the main conguration
le,we call PHP include() to include the rest conguration les and merge them
into a complete conguration array.
2.3.2 Application Base Directory
Application base directory refers to the root directory that contains all security-sensitive
PHP scripts and data.By default,it is a subdirectory named protected that is located
under the directory containing the entry script.It can be customized via setting the
basePath property in the.
Contents under the application base directory should be protected from being accessed by
Web users.With Apache HTTP server,this can be done easily by placing a.htaccess
le under the base directory.The content of the.htaccess le is as follows,
deny from all
2.3.3 Application Component
Functionalities of application can be easily customized and enriched with itsexible com-
ponent architecture.Application manages a set of application components,each imple-
menting specic features.For example,application resolves a user request with the help
of CUrlManager and CHttpRequest components.
By conguring the components property of application,we can customize the class and
property values of any application component used in an application.For example,we
can congure CMemCache component so that it can use multiple memcache servers for
caching,
array(
......
'components'=>array(
......
'cache'=>array(
'class'=>'CMemCache',
'servers'=>array(
array('host'=>'server1','port'=>11211,'weight'=>60),
array('host'=>'server2','port'=>11211,'weight'=>40),
),
),
),
)
22 2.Fundamentals
In the above,we add the cache element to the components array.The cache element states
that the class of the component is CMemCache and its servers property should be initialized
as such.
To access an application component,use Yii::app()->ComponentID,where ComponentID
refers to the ID of the component (e.g.Yii::app()->cache).
An application component may be disabled by setting enabled to be false in its congu-
ration.Null is returned when we access a disabled component.
Tip:By default,application components are created on demand.This means an
application component may not be created at all if it is not accessed during a
user request.As a result,the overall performance may not be degraded even if
an application is congured with many components.Some application components
(e.g.CLogRouter) may need to be created no matter they are accessed or not.To
do so,list their IDs in the preload property of the application.
2.3.4 Core Application Components
Yii predenes a set of core application components to provide features common among
Web applications.For example,the request component is used to resolve user requests
and provide information such as URL,cookies.By conguring the properties of these core
components,we can change the default behaviors of Yii in nearly every aspect.
Below we list the core components that are pre-declared by CWebApplication.
assetManager:CAssetManager - manages the publishing of private asset les.
authManager:CAuthManager - manages role-based access control (RBAC).
cache:CCache - provides data caching functionality.Note,you must specify the
actual class (e.g.CMemCache,CDbCache).Otherwise,null will be returned when
you access this component.
clientScript:CClientScript - manages client scripts (javascripts and CSS).
coreMessages:CPhpMessageSource - provides translated core messages used by Yii
framework.
db:CDbConnection - provides the database connection.Note,you must congure
its connectionString property in order to use this component.
errorHandler:CErrorHandler - handles uncaught PHP errors and exceptions.
2.3 Application 23
format:CFormatter - formats data values for display purpose.This has been avail-
able since version 1.1.0.
messages:CPhpMessageSource - provides translated messaged used by Yii applica-
tion.
request:CHttpRequest - provides information related with user requests.
securityManager:CSecurityManager - provides security-related services,such as
hashing,encryption.
session:CHttpSession - provides session-related functionalities.
statePersister:CStatePersister - provides global state persistence method.
urlManager:CUrlManager - provides URL parsing and creation functionality.
user:CWebUser - represents the identity information of the current user.
themeManager:CThemeManager - manages themes.
2.3.5 Application Lifecycles
When handling a user request,an application will undergo the following lifecycles:
1.Pre-initializes the application with CApplication::preinit();
2.Set up class autoloader and error handling;
3.Register core application components;
4.Load application conguration;
5.Initialize the application with CApplication::init()
Register application behaviors;
Load static application components;
6.Raise onBeginRequest event;
7.Process the user request:
Resolve the user request;
Create controller;
Run controller;
7.Raise onEndRequest event;
24 2.Fundamentals
2.4 Controller
A controller is an instance of CController or its child class.It is created by application
when the user requests for it.When a controller runs,it performs the requested action
which usually brings in the needed models and renders an appropriate view.An action,
at its simplest form,is just a controller class method whose name starts with action.
A controller has a default action.When the user request does not specify which action to
execute,the default action will be executed.By default,the default action is named as
index.It can be changed by setting CController::defaultAction.
Below is the minimal code needed by a controller class.Since this controller does not
dene any action,requesting for it would throw an exception.
class SiteController extends CController
f
g
2.4.1 Route
Controllers and actions are identied by IDs.Controller ID is in the format of path/
to/xyz which corresponds to the controller class le protected/controllers/path/to/
XyzController.php,where the token xyz should be replaced by actual names (e.g.post cor-
responds to protected/controllers/PostController.php).Action ID is the action method
name without the action prex.For example,if a controller class contains a method named
actionEdit,the ID of the corresponding action would be edit.
Note:Before version 1.0.3,the controller ID format was path.to.xyz instead of
path/to/xyz.
Users request for a particular controller and action in terms of route.A route is formed
by concatenating a controller ID and an action ID separated by a slash.For example,the
route post/edit refers to PostController and its edit action.And by default,the URL
http://hostname/index.php?r=post/edit would request for this controller and action.
Note:By default,routes are case-sensitive.Since version 1.0.1,it is possible to
make routes case-insensitive by setting CUrlManager::caseSensitive to be false in
the application conguration.When in case-insensitive mode,make sure you follow
the convention that directories containing controller class les are in lower case,and
both controller map and action map are using keys in lower case.
2.4 Controller 25
Since version 1.0.3,an application can contain modules.The route for a controller action
inside a module is in the format of moduleID/controllerID/actionID.For more details,see
the section about modules.
2.4.2 Controller Instantiation
A controller instance is created when CWebApplication handles an incoming request.
Given the ID of the controller,the application will use the following rules to determine
what the controller class is and where the class le is located.
If CWebApplication::catchAllRequest is specied,a controller will be created based
on this property,and the user-specied controller ID will be ignored.This is mainly
used to put the application under maintenance mode and display a static notice
page.
If the ID is found in CWebApplication::controllerMap,the corresponding controller
conguration will be used to create the controller instance.
If the ID is in the format of'path/to/xyz',the controller class name is assumed to
be XyzController and the corresponding class le is protected/controllers/path/
to/XyzController.php.For example,a controller IDadmin/user would be resolved as
the controller class UserController and the class le protected/controllers/admin/
UserController.php.If the class le does not exist,a 404 CHttpException will be
raised.
In case when modules are used (available since version 1.0.3),the above process is slighly
dierent.In particular,the application will check if the ID refers to a controller inside
a module,and if so,the module instance will be created rst followed by the controller
instance.
2.4.3 Action
As aforementioned,an action can be dened as a method whose name starts with the
word action.A more advanced way is to dene an action class and ask the controller to
instantiate it when requested.This allows actions to be reused and thus introduces more
reusability.
To dene a new action class,do the following:
class UpdateAction extends CAction
f
26 2.Fundamentals
public function run()
f
//place the action logic here
g
g
In order for the controller to be aware of this action,we override the actions() method of
our controller class:
class PostController extends CController
f
public function actions()
f
return array(
'edit'=>'application.controllers.post.UpdateAction',
);
g
g
In the above,we use the path alias application.controllers.post.UpdateAction to specify
that the action class le is protected/controllers/post/UpdateAction.php.
Writing class-based actions,we can organize an application in a modular fashion.For
example,the following directory structure may be used to organize the code for controllers:
protected/
controllers/
PostController.php
UserController.php
post/
CreateAction.php
ReadAction.php
UpdateAction.php
user/
CreateAction.php
ListAction.php
ProfileAction.php
UpdateAction.php
2.4.4 Filter
Filter is a piece of code that is congured to be executed before and/or after a controller
action executes.For example,an access control lter may be executed to ensure that the
user is authenticated before executing the requested action;a performance lter may be
used to measure the time spent in the action execution.
2.4 Controller 27
An action can have multiple lters.The lters are executed in the order that they appear
in the lter list.A lter can prevent the execution of the action and the rest of the
unexecuted lters.
A lter can be dened as a controller class method.The method name must begin with
filter.For example,the existence of the filterAccessControl method denes a lter
named accessControl.The lter method must be of the signature:
public function filterAccessControl($filterChain)
f
//call $filterChain->run() to continue filtering and action execution
g
where $filterChain is an instance of CFilterChain which represents the lter list associated
with the requested action.Inside the lter method,we can call $filterChain->run() to
continue ltering and action execution.
A lter can also be an instance of CFilter or its child class.The following code denes a
new lter class:
class PerformanceFilter extends CFilter
f
protected function preFilter($filterChain)
f
//logic being applied before the action is executed
return true;//false if the action should not be executed
g
protected function postFilter($filterChain)
f
//logic being applied after the action is executed
g
g
To apply lters to actions,we need to override the CController::filters() method.The
method should return an array of lter congurations.For example,
class PostController extends CController
f
......
public function filters()
f
return array(
'postOnly + edit,create',
28 2.Fundamentals
array(
'application.filters.PerformanceFilter - edit,create',
'unit'=>'second',
),
);
g
g
The above code species two lters:postOnly and PerformanceFilter.The postOnly l-
ter is method-based (the corresponding lter method is dened in CController already);
while the PerformanceFilter lter is object-based.The path alias application.filters.
PerformanceFilter species that the lter class le is protected/filters/PerformanceFilter.
We use an array to congure PerformanceFilter so that it may be used to initialize the
property values of the lter object.Here the unit property of PerformanceFilter will be
initialized as'second'.
Using the plus and the minus operators,we can specify which actions the lter should and
should not be applied to.In the above,the postOnly should be applied to the edit and
create actions,while PerformanceFilter should be applied to all actions EXCEPT edit
and create.If neither plus nor minus appears in the lter conguration,the lter will be
applied to all actions.
2.5 Model
A model is an instance of CModel or its child class.Models are used to keep data and
their relevant business rules.
A model represents a single data object.It could be a row in a database table or a form
of user inputs.Each eld of the data object is represented as an attribute of the model.
The attribute has a label and can be validated against a set of rules.
Yii implements two kinds of models:form model and active record.They both extend
from the same base class CModel.
A form model is an instance of CFormModel.Form model is used to keep data collected
from user inputs.Such data are often collected,used and then discarded.For example,on
a login page,we can use a formmodel to represent the username and password information
that are provided by an end user.For more details,please refer to Working with Form
Active Record (AR) is a design pattern used to abstract database access in an object-
oriented fashion.Each AR object is an instance of CActiveRecord or its child class,
representing a single row in a database table.The elds in the row are represented as
properties of the AR object.Details about AR can be found in Active Record.
2.6 View 29
2.6 View
A view is a PHP script consisting of mainly elements of user interface.It can contain PHP
statements,but it is recommended that these statements should not alter data models and
should remain relatively simple.For the spirit of separation of logic and presentation,large
chunk of logic should be placed in controller or model instead of view.
A view has a name which is used to identify the view script le when rendering.The
name of a view is the same as the name of its view script le.For example,view edit
refers to a view script le named as edit.php.To render a view,call CController::render()
with the name of the view.The method will look for the corresponding view le under
the directory protected/views/ControllerID.
Inside the view script,we can access the controller instance using $this.We can thus pull
in any property of the controller by evaluating $this->propertyName in the view.
We can also use the following push approach to pass data to the view:
$this->render('edit',array(
'var1'=>$value1,
'var2'=>$value2,
));
In the above,the render() method will extract the second array parameter into variables.
As a result,in the view script we can access local variables $var1 and $var2.
2.6.1 Layout
Layout is a special view that is used to decorate views.It usually contains portions of
user interface that are common among several views.For example,a layout may contain
header and footer portions and embed the content view in between,
......header here......
<?php echo $content;?>
......footer here......
where $content stores the rendering result of the content view.
Layout is implicitly applied when calling render().By default,the view script protected/
views/layouts/main.php is used as the layout.This can be customized by changing either
CWebApplication::layout or CController::layout.To render a view without applying any
layout,call renderPartial() instead.
30 2.Fundamentals
2.6.2 Widget
A widget is an instance of CWidget or its child class.It is a component mainly for
presentational purpose.Widgets are usually embedded in a view script to generate some
complex yet self-contained user interface.For example,a calendar widget can be used
to render a complex calendar user interface.Widgets enable better reusability in user
interface.
To use a widget,do as follows in a view script:
<?php $this->beginWidget('path.to.WidgetClass');?>
...body content that may be captured by the widget...
<?php $this->endWidget();?>
or
<?php $this->widget('path.to.WidgetClass');?>
The latter is used when the widget does not need any body content.
Widgets can be congured to customize its behaviors.This is done by settings their initial
property values when calling CBaseController::beginWidget or CBaseController::widget.
For example,when using CMaskedTextField widget,we would like to specify the mask
being used.We can do so by passing an array of those property initial values as fol-
lows,where the array keys are property names and array values the initial values of the
corresponding widget properties:
<?php
$this->widget('CMaskedTextField',array(
'mask'=>'99/99/9999'
));
?>
To dene a new widget,extend CWidget and override its init() and run() methods:
class MyWidget extends CWidget
f
public function init()
f
//this method is called by CController::beginWidget()
g
2.7 Component 31
public function run()
f
//this method is called by CController::endWidget()
g
g
Like a controller,a widget can also have its own view.By default,widget view les are
located under the views subdirectory of the directory containing the widget class le.
These views can be rendered by calling CWidget::render(),similar to that in controller.
The only dierence is that no layout will be applied to a widget view.Also,$this in the
view refers to the widget instance instead of the controller instance.
2.6.3 System View
System views refer to the views used by Yii to display error and logging information.For
example,when a user requests for a non-existing controller or action,Yii will throw an
exception explaining the error.Yii displays the exception using a specic system view.
The naming of system views follows some rules.Names like errorXXX refer to views for
displaying CHttpException with error code XXX.For example,if CHttpException is raised
with error code 404,the error404 view will be displayed.
Yii provides a set of default system views located under framework/views.They can be
customized by creating the same-named view les under protected/views/system.
2.7 Component
Yii applications are built upon components which are objects written to a specication.
A component is an instance of CComponent or its derived class.Using a component
mainly involves accessing its properties and raising/handling its events.The base class
CComponent species how to dene properties and events.
2.7.1 Component Property
A component property is like an object's public member variable.We can read its value
or assign a value to it.For example,
$width=$component->textWidth;//get the textWidth property
$component->enableCaching=true;//set the enableCaching property
To dene a component property,we can simply declare a public member variable in the
component class.A moreexible way,however,is by dening getter and setter methods
32 2.Fundamentals
like the following:
public function getTextWidth()
f
return $this->
textWidth;
g
public function setTextWidth($value)
f
$this->
textWidth=$value;
g
The above code denes a writable property named textWidth (the name is case-insensitive).
When reading the property,getTextWidth() is invoked and its returned value becomes the
property value;Similarly,when writing the property,setTextWidth() is invoked.If the
setter method is not dened,the property would be read-only and writing it would throw
an exception.Using getter and setter methods to dene a property has the benet that
additional logic (e.g.performing validation,raising events) can be executed when reading
and writing the property.
Note:There is a slight dierence between a property dened via getter/setter
methods and a class member variable.The name of the former is case-insensitive
while the latter is case-sensitive.
2.7.2 Component Event
Component events are special properties that take methods (called event handlers) as
their values.Attaching (assigning) a method to an event will cause the method to be
invoked automatically at the places where the event is raised.Therefore,the behavior of
a component can be modied in a way that may not be foreseen during the development
of the component.
A component event is dened by dening a method whose name starts with on.Like
property names dened via getter/setter methods,event names are case-insensitive.The
following code denes an onClicked event:
public function onClicked($event)
f
$this->raiseEvent('onClicked',$event);
g
2.7 Component 33
where $event is an instance of CEvent or its child class representing the event parameter.
We can attach a method to this event as follows:
$component->onClicked=$callback;
where $callback refers to a valid PHP callback.It can be a global function or a class
method.If the latter,the callback must be given as an array:array($object,'methodName').
The signature of an event handler must be as follows:
function methodName($event)
f
......
g
where $event is the parameter describing the event (it originates from the raiseEvent()
call).The $event parameter is an instance of CEvent or its derived class.At the minimum,
it contains the information about who raises the event.
Starting from version 1.0.10,an event handler can also be an anonymous function which
is supported by PHP 5.3 or above.For example,
$component->onClicked=function($event) f
......
g
If we call onClicked() now,the onClicked event will be raised (inside onClicked()),and
the attached event handler will be invoked automatically.
An event can be attached with multiple handlers.When the event is raised,the handlers
will be invoked in the order that they are attached to the event.If a handler decides to
prevent the rest handlers from being invoked,it can set $event->handled to be true.
2.7.3 Component Behavior
Starting fromversion 1.0.2,a component has added support for mixin and can be attached
with one or several behaviors.A behavior is an object whose methods can be'inherited'
by its attached component through the means of collecting functionality instead of spe-
cialization (i.e.,normal class inheritance).A component can be attached with several
behaviors and thus achieve'multiple inheritance'.
34 2.Fundamentals
Behavior classes must implement the IBehavior interface.Most behaviors can extend
from the CBehavior base class.If a behavior needs to be attached to a model,it may also
extend from CModelBehavior or CActiveRecordBehavior which implements additional
features specifc for models.
To use a behavior,it must be attached to a component rst by calling the behavior's
attach() method.Then we can call a behavior method via the component:
//$name uniquely identifies the behavior in the component
$component->attachBehavior($name,$behavior);
//test() is a method of $behavior
$component->test();
An attached behavior can be accessed like a normal property of the component.For
example,if a behavior named tree is attached to a component,we can obtain the reference
to this behavior object using:
$behavior=$component->tree;
//equivalent to the following:
//$behavior=$component->asa('tree');
A behavior can be temporarily disabled so that its methods are not available via the
component.For example,
$component->disableBehavior($name);
//the following statement will throw an exception
$component->test();
$component->enableBehavior($name);
//it works now
$component->test();
It is possible that two behaviors attached to the same component have methods of the
same name.In this case,the method of the rst attached behavior will take precedence.
When used together with,behaviors are even more powerful.A behavior,when being
attached to a component,can attach some of its methods to some events of the component.
By doing so,the behavior gets a chance to observe or change the normal executionow
of the component.
Starting from version 1.1.0,a behavior's properties can also be accessed via the compo-
nent it is attached to.The properties include both the public member variables and the
2.8 Module 35
properties dened via getters and/or setters of the behavior.For example,if a behavior
has a property named xyz and the behavior is attached to a component $a.Then we can
use the expression $a->xyz to access the behavior's property.
2.8 Module
Note:Support for module has been available since version 1.0.3.
A module is a self-contained software unit that consists of models,views,controllers and
other supporting components.In many aspects,a module resembles to an application.
The main dierence is that a module cannot be deployed alone and it must reside inside
of an application.Users can access the controllers in a module like they do with normal
application controllers.
Modules are useful in several scenarios.For a large-scale application,we may divide it into
several modules,each being developed and maintained separately.Some commonly used
features,such as user management,comment management,may be developed in terms of
modules so that they can be reused easily in future projects.
2.8.1 Creating Module
A module is organized as a directory whose name serves as its unique ID.The structure
of the module directory is similar to that of the application base directory.The following
shows the typical directory structure of a module named forum:
forum/
ForumModule.php the module class file
components/containing reusable user components
views/containing view files for widgets
controllers/containing controller class files
DefaultController.php the default controller class file
extensions/containing third-party extensions
models/containing model class files
views/containing controller view and layout files
layouts/containing layout view files
default/containing view files for DefaultController
index.php the index view file
A module must have a module class that extends from CWebModule.The class name
is determined using the expression ucfirst($id).'Module',where $id refers to the mod-
ule ID (or the module directory name).The module class serves as the central place
36 2.Fundamentals
for storing information shared among the module code.For example,we can use CWeb-
Module::params to store module parameters,and use CWebModule::components to share
application components at the module level.
Tip:We can use the module generator in Gii to create the basic skeleton of a new
module.
2.8.2 Using Module
To use a module,rst place the module directory under modules of the application base
directory.Then declare the module ID in the modules property of the application.For
example,in order to use the above forum module,we can use the following application
conguration:
return array(
......
'modules'=>array('forum',...),
......
);
A module can also be congured with initial property values.The usage is very similar
to conguring application components.For example,the forum module may have a prop-
erty named postPerPage in its module class which can be congured in the application
conguration as follows:
return array(
......
'modules'=>array(
'forum'=>array(
'postPerPage'=>20,
),
),
......
);
The module instance may be accessed via the module property of the currently active
controller.Through the module instance,we can then access information that are shared
at the module level.For example,in order to access the above postPerPage information,
we can use the following expression:
$postPerPage=Yii::app()->controller->module->postPerPage;
2.9 Path Alias and Namespace 37
//or the following if $this refers to the controller instance
//$postPerPage=$this->module->postPerPage;
A controller action in a module can be accessed using the route moduleID/controllerID/
actionID.For example,assuming the above forum module has a controller named PostController,
we can use the route forum/post/create to refer to the create action in this controller.The
corresponding URL for this route would be http://www.example.com/index.php?r=forum/
post/create.
Tip:If a controller is in a sub-directory of controllers,we can still use the
above route format.For example,assuming PostController is under forum/
controllers/admin,we can refer to the create action using forum/admin/post/
create.
2.8.3 Nested Module
Modules can be nested.That is,a module can contain another module.We call the
former parent module while the latter child module.Child modules must be placed under
the modules directory of the parent module.To access a controller action in a child module,
we should use the route parentModuleID/childModuleID/controllerID/actionID.
2.9 Path Alias and Namespace
Yii uses path aliases extensively.A path alias is associated with a directory or le path.
It is specied in dot syntax,similar to that of widely adopted namespace format:
RootAlias.path.to.target
where RootAlias is the alias of some existing directory.By calling YiiBase::setPathOfAlias(),
we can dene new path aliases.For convenience,Yii predenes the following root aliases:
system:refers to the Yii framework directory;
zii:refers to the Zii library directory;
application:refers to the application's base directory;
webroot:refers to the directory containing the entry script le.This alias has been
available since version 1.0.3.
38 2.Fundamentals
ext:refers to the directory containing all third-party extensions.This alias has been
available since version 1.0.8.
Additionally,if the application uses modules,a root alias is also predened for each module
IDand refers to the base path of the corresponding module.This feature has been available
since version 1.0.3.
By using YiiBase::getPathOfAlias(),an alias can be translated to its corresponding path.
For example,system.web.CController would be translated as yii/framework/web/CController.
Using aliases,it is very convenient to import the denition of a class.For example,if we
want to include the denition of the CController class,we can call the following:
Yii::import('system.web.CController');
The import method diers frominclude and require in that it is more ecient.The class
denition being imported is actually not included until it is referenced for the rst time.
Importing the same namespace multiple times is also much faster than include
once and
require
once.
Tip:When referring to a class dened by the Yii framework,we do not need to
import or include it.All core Yii classes are pre-imported.
We can also use the following syntax to import a whole directory so that the class les
under the directory can be automatically included when needed.
Yii::import('system.web.*');
Besides import,aliases are also used in many other places to refer to classes.For example,
an alias can be passed to Yii::createComponent() to create an instance of the corresponding
class,even if the class le was not included previously.
Do not confuse path alias with namespace.A namespace refers to a logical grouping of
some class names so that they can be dierentiated from other class names even if their
names are the same,while path alias is used to refer to a class le or directory.Path alias
does not conict with namespace.
2.10 Conventions 39
Tip:Because PHP prior to 5.3.0 does not support namespace intrinsically,you
cannot create instances of two classes who have the same name but with dierent
denitions.For this reason,all Yii framework classes are prexed with a letter'C'
(meaning'class') so that they can be dierentiated from user-dened classes.It
is recommended that the prex'C'be reserved for Yii framework use only,and
user-dened classes be prexed with other letters.
2.10 Conventions
Yii favors conventions over congurations.Follow the conventions and one can create
sophisticated Yii applications without writing and managing complex congurations.Of
course,Yii can still be customized in nearly every aspect with congurations when needed.
Below we describe conventions that are recommended for Yii programming.For conve-
nience,we assume that WebRoot is the directory that a Yii application is installed at.
2.10.1 URL
By default,Yii recognizes URLs with the following format:
http://hostname/index.php?r=ControllerID/ActionID
The r GET variable refers to the route that can be resolved by Yii into controller and
action.If ActionID is omitted,the controller will take the default action (dened via CCon-
troller::defaultAction);and if ControllerID is also omitted (or the r variable is absent),the
application will use the default controller (dened via CWebApplication::defaultController).
With the help of CUrlManager,it is possible to create and recognize more SEO-friendly
URLs,such as http://hostname/ControllerID/ActionID.html.This feature is covered in
detail in URL Management.
2.10.2 Code
Yii recommends naming variables,functions and class types in camel case which capitalizes
each word in the name and joins them without spaces.Variable and function names
should have their rst word all in lower-case,in order to dierentiate from class names
(e.g.$basePath,runController(),LinkPager).For private class member variables,it is
recommended to prex their names with an underscore character (e.g.$
actionList).
Because namespace is not supported prior to PHP 5.3.0,it is recommended that classes
40 2.Fundamentals
be named in some unique way to avoid name conict with third-party classes.For this
reason,all Yii framework classes are prexed with letter"C".
A special rule for controller class names is that they must be appended with the word
Controller.The controller ID is then dened as the class name with rst letter in lower
case and the word Controller truncated.For example,the PageController class will
have the ID page.This rule makes the application more secure.It also makes the URLs
related with controllers a bit cleaner (e.g./index.php?r=page/index instead of/index.
php?r=PageController/index).
2.10.3 Conguration
A conguration is an array of key-value pairs.Each key represents the name of a prop-
erty of the object to be congured,and each value the corresponding property's initial
value.For example,array('name'=>'My application','basePath'=>'./protected') ini-
tializes the name and basePath properties to their corresponding array values.
Any writable properties of an object can be congured.If not congured,the properties
will take their default values.When conguring a property,it is worthwhile to read the
corresponding documentation so that the initial value can be given properly.
2.10.4 File
Conventions for naming and using les depend on their types.
Class les should be named after the public class they contain.For example,the CCon-
troller class is in the CController.php le.A public class is a class that may be used by
any other classes.Each class le should contain at most one public class.Private classes
(classes that are only used by a single public class) may reside in the same le with the
public class.
View les should be named after the view name.For example,the index view is in the
index.php le.A view le is a PHP script le that contains HTML and PHP code mainly
for presentational purpose.
Conguration les can be named arbitrarily.A conguration le is a PHP script whose
sole purpose is to return an associative array representing the conguration.
2.10.5 Directory
Yii assumes a default set of directories used for various purposes.Each of them can be
customized if needed.
2.10 Conventions 41
WebRoot/protected:this is the application base directory holding all security-sensitive
PHP scripts and data les.Yii has a default alias named application associated
with this path.This directory and everything under should be protected from being
accessed by Web users.It can be customized via CWebApplication::basePath.
WebRoot/protected/runtime:this directory holds private temporary les generated
during runtime of the application.This directory must be writable by Web server
process.It can be customized via CApplication::runtimePath.
WebRoot/protected/extensions:this directory holds all third-party extensions.It
can be customized via CApplication::extensionPath.
WebRoot/protected/modules:this directory holds all application modules,each rep-
resented as a subdirectory.
WebRoot/protected/controllers:this directory holds all controller class les.It can
be customized via CWebApplication::controllerPath.
WebRoot/protected/views:this directory holds all view les,including controller
views,layout views and system views.It can be customized via CWebApplica-
tion::viewPath.
WebRoot/protected/views/ControllerID:this directory holds view les for a single
controller class.Here ControllerID stands for the ID of the controller.It can be
customized via CController::viewPath.
WebRoot/protected/views/layouts:this directory holds all layout view les.It can
be customized via CWebApplication::layoutPath.
WebRoot/protected/views/system:this directory holds all system view les.System
views are templates used in displaying exceptions and errors.It can be customized
via CWebApplication::systemViewPath.
WebRoot/assets:this directory holds published asset les.An asset le is a private
le that may be published to become accessible to Web users.This directory must be
writable by Web server process.It can be customized via CAssetManager::basePath.
WebRoot/themes:this directory holds various themes that can be applied to the appli-
cation.Each subdirectory represents a single theme whose name is the subdirectory
name.It can be customized via CThemeManager::basePath.
2.10.6 Database
Most Web applications are backed by some database.For best practice,we propose the
following naming conventions for database tables and columns.Note that they are not
required by Yii.
42 2.Fundamentals
Both database tables and columns are named in lower case.
Words in a name should be separated using underscores (e.g.product
order).
For table names,you may use either singular or plural names,but not both.For
simplicity,we recommend using singular names.
Table names may be prexed with a common token such as tbl
.This is especially
useful when the tables of an application coexist in the same database with the tables
of another application.The two sets of tables can be readily separate by using
dierent table name prexes.
2.11 Development Workow
Having described the fundamental concepts of Yii,we show the common workow for
developing a web application using Yii.The workow assumes that we have done the
requirement analysis as well as the necessary design analysis for the application.
1.Create the skeleton directory structure.The yiic tool described in Creating First
Yii Application can be used to speed up this step.
2.Congure the application.This is done by modifying the application conguration
le.This step may also require writing some application components (e.g.the user
component).
3.Create a model class for each type of data to be managed.Again,yiic can be used
to automatically generate the active record class for each interested database table.
4.Create a controller class for each type of user requests.How to classify user requests
depends on the actual requirement.In general,if a model class needs to be accessed
by users,it should have a corresponding controller class.The yiic tool can automate
this step,too.
5.Implement actions and their corresponding views.This is where the real work needs
to be done.
6.Congure necessary action lters in controller classes.
7.Create themes if the theming feature is required.
8.Create translated messages if internationalization is required.
9.Spot data and views that can be cached and apply appropriate caching techniques.
10.Final tune up and deployment.
2.11 Development Workow 43
For each of the above steps,test cases may need to be created and performed.
44 2.Fundamentals
Chapter 3
Working with Forms
3.1 Working with Form
Collecting user data via HTML forms is one of the major tasks in Web application de-
velopment.Besides designing forms,developers need to populate the form with existing
data or default values,validate user input,display appropriate error messages for invalid
input,and save the input to persistent storage.Yii greatly simplies this workow with
its MVC architecture.
The following steps are typically needed when dealing with forms in Yii:
1.Create a model class representing the data elds to be collected;
2.Create a controller action with code that responds to form submission.
3.Create a form in the view script le associated with the controller action.
In the next subsections,we describe each of these steps in detail.
3.2 Creating Model
Before writing the HTML code needed by a form,we should decide what kind of data we
are expecting fromend users and what rules these data should comply with.A model class
can be used to record these information.A model,as dened in the Model subsection,is
the central place for keeping user inputs and validating them.
Depending on how we make use of the user input,we can create two types of model.If
the user input is collected,used and then discarded,we would create a form model;if the
user input is collected and saved into database,we would use an active record instead.
Both types of model share the same base class CModel which denes the common interface
needed by form.
46 3.Working with Forms
Note:We are mainly using form models in the examples of this section.However,
the same can also be applied to active record models.
3.2.1 Dening Model Class
Belowwe create a LoginForm model class used to collect user input on a login page.Because
the login information is only used to authenticate the user and does not need to be saved,
we create LoginForm as a form model.
class LoginForm extends CFormModel
f
public $username;
public $password;
public $rememberMe=false;
g
Three attributes are declared in LoginForm:$username,$password and $rememberMe.They
are used to keep the user-entered username and password,and the option whether the
user wants to remember his login.Because $rememberMe has a default value false,the
corresponding option when initially displayed in the login form will be unchecked.
Info:Instead of calling these member variables properties,we use the name at-
tributes to dierentiate them from normal properties.An attribute is a property
that is mainly used to store data coming from user input or database.
3.2.2 Declaring Validation Rules
Once a user submits his inputs and the model gets populated,we need to make sure the
inputs are valid before using them.This is done by performing validation of the inputs
against a set of rules.We specify the validation rules in the rules() method which should
return an array of rule congurations.
class LoginForm extends CFormModel
f
public $username;
public $password;
public $rememberMe=false;
private $
identity;
3.2 Creating Model 47
public function rules()
f
return array(
array('username,password','required'),
array('rememberMe','boolean'),
array('password','authenticate'),
);
g
public function authenticate($attribute,$params)
f
$this->
identity=new UserIdentity($this->username,$this->password);
if(!$this->
identity->authenticate())
$this->addError('password','Incorrect username or password.');
g
g
The above code species that username and password are both required,password should
be authenticated,and rememberMe should be a boolean.
Each rule returned by rules() must be of the following format:
array('AttributeList','Validator','on'=>'ScenarioList',...additional options)
where AttributeList is a string of comma-separated attribute names which need to be
validated according to the rule;Validator species what kind of validation should be
performed;the on parameter is optional which species a list of scenarios where the rule
should be applied;and additional options are name-value pairs which are used to initialize
the corresponding validator's property values.
There are three ways to specify Validator in a validation rule.First,Validator can be
the name of a method in the model class,like authenticate in the above example.The
validator method must be of the following signature:
/**
* @param string the name of the attribute to be validated
* @param array options specified in the validation rule
*/
public function ValidatorName($attribute,$params) f...g
Second,Validator can be the name of a validator class.When the rule is applied,an
instance of the validator class will be created to perform the actual validation.The
additional options in the rule are used to initialize the instance's attribute values.A
validator class must extend from CValidator.
48 3.Working with Forms
Note:When specifying rules for an active record model,we can use a special
option named on.The option can be either'insert'or'update'so that the rule
is applied only when inserting or updating the record,respectively.If not set,the
rule would be applied in both cases when save() is called.
Third,Validator can be a predened alias to a validator class.In the above example,the
name required is the alias to CRequiredValidator which ensures the attribute value being
validated is not empty.Below is the complete list of predened validator aliases:
boolean:alias of CBooleanValidator,ensuring the attribute has a value that is either
CBooleanValidator::trueValue or CBooleanValidator::falseValue.
captcha:alias of CCaptchaValidator,ensuring the attribute is equal to the verica-
tion code displayed in a CAPTCHA.
compare:alias of CCompareValidator,ensuring the attribute is equal to another
attribute or constant.
email:alias of CEmailValidator,ensuring the attribute is a valid email address.
default:alias of CDefaultValueValidator,assigning a default value to the specied
attributes.
exist:alias of CExistValidator,ensuring the attribute value can be found in the
specied table column.
file:alias of CFileValidator,ensuring the attribute contains the name of an up-
loaded le.
filter:alias of CFilterValidator,transforming the attribute with a lter.
in:alias of CRangeValidator,ensuring the data is among a pre-specied list of
values.
length:alias of CStringValidator,ensuring the length of the data is within certain
range.
match:alias of CRegularExpressionValidator,ensuring the data matches a regular
expression.
numerical:alias of CNumberValidator,ensuring the data is a valid number.
required:alias of CRequiredValidator,ensuring the attribute is not empty.
type:alias of CTypeValidator,ensuring the attribute is of specic data type.
3.2 Creating Model 49
unique:alias of CUniqueValidator,ensuring the data is unique in a database table
column.
url:alias of CUrlValidator,ensuring the data is a valid URL.
Below we list some examples of using the predened validators:
//username is required
array('username','required'),
//username must be between 3 and 12 characters
array('username','length','min'=>3,'max'=>12),
//when in register scenario,password must match password2
array('password','compare','compareAttribute'=>'password2','on'=>'register'),
//when in login scenario,password must be authenticated
array('password','authenticate','on'=>'login'),
3.2.3 Securing Attribute Assignments
After a model instance is created,we often need to populate its attributes with the data
submitted by end-users.This can be done conveniently using the following massive as-
signment:
$model=new LoginForm;
if(isset($
POST['LoginForm']))
$model->attributes=$
POST['LoginForm'];
The last statement is called massive assignment which assigns every entry in $
POST['LoginForm']
to the corresponding model attribute.It is equivalent to the following assignments:
foreach($
POST['LoginForm'] as $name=>$value)
f
if($name is a safe attribute)
$model->$name=$value;
g
It is crucial to determine which attributes are safe.For example,if we expose the primary
key of a table to be safe,then an attacker could get a chance to modify the primary key
of the given record and thus tamper the data he is not authorized to.
The policy of deciding which attributes are safe is dierent in version 1.0 and 1.1.In the
following,we will describe them separately.
50 3.Working with Forms
Safe Attributes in 1.1
In version 1.1,an attribute is considered safe if it appears in a validation rule that is
applicable in the given scenario.For example,
array('username,password','required','on'=>'login,register'),
array('email','required','on'=>'register'),
In the above,the username and password attributes are required in login scenario,while
the username,password and email attributes are required in register scenario.As a result,
if we perform a massive assign when in login scenario,only username and password will
be massively assigned since they are the only attributes appearing in the validation rules
for login.On the other hand,if the scenario is register,the three attributes can all be
massively assigned.
//in login scenario
$model=new User('login');
if(isset($
POST['User']))
$model->attributes=$
POST['User'];
//in register scenario
$model=new User('register');
if(isset($
POST['User']))
$model->attributes=$
POST['User'];
So why do we use such a policy to determine if an attribute is safe or not?The rationale
behind is that if an attribute already has one or several validation rules to check its validity,
what else should we worry about it?
It is important to remember that validation rules are used to check user input data rather
than the data that we generate in the code (e.g.timestamp,auto-generated primary key).
Therefore,DO NOT add validation rules for those attributes which do not expect inputs
from end-users.
Sometimes,we want to declare an attribute to be safe,even though we do not really have
any specic rule for it.An example is an article's content attribute which can take any
user input.We can use the special safe rule to achieve this goal:
array('content','safe')
For completeness,there is also an unsafe rule which is used to explicitly declare an at-
tribute to be unsafe:
3.2 Creating Model 51
array('permission','unsafe')
The unsafe rule is rarely used,and it is an exception to our previous denition of safe
attributes.
Safe Attributes in 1.0
In version 1.0,the task of deciding whether a data entry is safe or not is based on the
return value of a method named safeAttributes and the specied scenario.By default,
the method returns all public member variables as safe attributes for CFormModel,while
it returns all table columns except the primary key as safe attributes for CActiveRecord.
We may override this method to limit safe attributes according to scenarios.For example,
a user model may contain many attributes,but in login scenario we only need to use
username and password attributes.We can specify this limit as follows:
public function safeAttributes()
f
return array(
parent::safeAttributes(),
'login'=>'username,password',
);
g
More accurately,the return value of the safeAttributes method should be of the following
structure:
array(
//these attributes can be massively assigned in any scenario
//that is not explicitly specified below
'attr1,attr2,...',
*
//these attributes can be massively assigned only in scenario 1
'scenario1'=>'attr2,attr3,...',
*
//these attributes can be massively assigned only in scenario 2
'scenario2'=>'attr1,attr3,...',
)
If the model is not scenario-sensitive (i.e.,it is only used in one scenario,or all scenarios
share the same set of safe attributes),the return value can be simplied as a single string:
'attr1,attr2,...'
52 3.Working with Forms
For data entries that are not safe,we need to assign them to the corresponding attributes
using individual assign statements,like the following:
$model->permission='admin';
$model->id=1;
3.2.4 Triggering Validation
Once a model is populated with user-submitted data,we can call CModel::validate() to
trigger the data validation process.The method returns a value indicating whether the
validation is successful or not.For CActiveRecord models,validation may also be auto-
matically triggered when we call its CActiveRecord::save() method.
We can set a scenario with the scenario property and therewith indicate which set of
validation rules should be applied.
Validation is performed in a scenario basis.The scenario property species which scenario
the model is being used in and which set of validation rules should be used.For example,
in the login scenario,we only want to validate the username and password inputs of a user
model;while in the register scenario,we need to validate more inputs,such as email,
address,etc.The following example shows how to perform validation in the register
scenario:
//creates a User model in register scenario.It is equivalent to:
//$model=new User;
//$model->scenario='register';
$model=new User('register');
//populates the input values into the model
$model->attributes=$
POST['User'];
//performs the validation
if($model->validate())//if the inputs are valid
...
else
...
The applicable scenarios that a rule is associated can be specied via the on option in
the rule.If the on option is not set,it means the rule will be used for all scenarios.For
example,
public function rules()
f
3.3 Creating Action 53
return array(
array('username,password','required'),
array('password
repeat','required','on'=>'register'),
array('password','compare','on'=>'register'),
);
g
The rst rule will be applied in all scenarios,while the next two rules will only be applied
in the register scenario.
3.2.5 Retrieving Validation Errors
Once validation is done,any possible errors will be stored in the model object.We can
retrieve the error messages by calling CModel::getErrors() and CModel::getError().The
dierence between the two methods is that the rst method will return all errors for the
specied model attribute while the second method will only return the rst error.
3.2.6 Attribute Labels
When designing a form,we often need to display a label for each input eld.The label
tells a user what kind of information he is expected to enter into the eld.Although we
can hardcode a label in a view,it would oer moreexibility and convenience if we specify
it in the corresponding model.
By default,CModel will simply return the name of an attribute as its label.This can be
customized by overriding the attributeLabels() method.As we will see in the following
subsections,specifying labels in the model allows us to create a form more quickly and
powerful.
3.3 Creating Action
Once we have a model,we can start to write logic that is needed to manipulate the model.
We place this logic inside a controller action.For the login form example,the following
code is needed:
public function actionLogin()
f
$model=new LoginForm;
if(isset($
POST['LoginForm']))
f
//collects user input data
$model->attributes=$
POST['LoginForm'];
//validates user input and redirect to previous page if validated
54 3.Working with Forms
if($model->validate())
$this->redirect(Yii::app()->user->returnUrl);
g
//displays the login form
$this->render('login',array('model'=>$model));
g
In the above,we rst create a LoginForm model instance;if the request is a POST request
(meaning the login form is submitted),we populate $model with the submitted data $
POST['LoginForm'];we then validate the input and if successful,redirect the user browser
to the page that previously needed authentication.If the validation fails,or if the action
is initially accessed,we render the login view whose content is to be described in the next
subsection.
Tip:In the login action,we use Yii::app()->user->returnUrl to get the URL of
the page that previously needed authentication.The component Yii::app()->user
is of type CWebUser (or its child class) which represents user session information
(e.g.username,status).For more details,see Authentication and Authorization.
Let's pay special attention to the following PHP statement that appears in the login
action:
$model->attributes=$
POST['LoginForm'];
As we described in Securing Attribute Assignments,this line of code populates the model
with the user submitted data.The attributes property is dened by CModel which
expects an array of name-value pairs and assigns each value to the corresponding model
attribute.So if $
POST['LoginForm'] gives us such an array,the above code would be
equivalent to the following lengthy one (assuming every needed attribute is present in the
array):
$model->username=$
POST['LoginForm']['username'];
$model->password=$
POST['LoginForm']['password'];
$model->rememberMe=$
POST['LoginForm']['rememberMe'];
Note:In order to let $
POST['LoginForm'] to give us an array instead of a string,
we stick to a convention when naming input elds in the view.In particular,for an
input eld corresponding to attribute a of model class C,we name it as C[a].For
example,we would use LoginForm[username] to name the input eld corresponding
to the username attribute.
3.4 Creating Form 55
The remaining task now is to create the login view which should contain an HTML form
with the needed input elds.
3.4 Creating Form
Writing the login view is straightforward.We start with a form tag whose action attribute
should be the URL of the login action described previously.We then insert labels and
input elds for the attributes declared in the LoginForm class.At the end we insert a
submit button which can be clicked by users to submit the form.All these can be done
in pure HTML code.
Yii provides a few helper classes to facilitate view composition.For example,to cre-
ate a text input eld,we can call CHtml::textField();to create a drop-down list,call
CHtml::dropDownList().
Info:One may wonder what is the benet of using helpers if they require similar
amount of code when compared with plain HTML code.The answer is that the
helpers can provide more than just HTML code.For example,the following code
would generate a text input eld which can trigger form submission if its value is
changed by users.
CHtml::textField($name,$value,array('submit'=>''));
It would otherwise require writing clumsy JavaScript everywhere.
In the following,we use CHtml to create the login form.We assume that the variable
$model represents LoginForm instance.
<div class="form">
<?php echo CHtml::beginForm();?>
<?php echo CHtml::errorSummary($model);?>
<div class="row">
<?php echo CHtml::activeLabel($model,'username');?>
<?php echo CHtml::activeTextField($model,'username')?>
</div>
<div class="row">
<?php echo CHtml::activeLabel($model,'password');?>
<?php echo CHtml::activePasswordField($model,'password')?>
</div>
56 3.Working with Forms
<div class="row rememberMe">
<?php echo CHtml::activeCheckBox($model,'rememberMe');?>
<?php echo CHtml::activeLabel($model,'rememberMe');?>
</div>
<div class="row submit">
<?php echo CHtml::submitButton('Login');?>
</div>
<?php echo CHtml::endForm();?>
</div><!-- form -->
The above code generates a more dynamic form.For example,CHtml::activeLabel()
generates a label associated with the specied model attribute.If the attribute has an
input error,the label's CSS class will be changed to error,which changes the appearance
of the label with appropriate CSS styles.Similarly,CHtml::activeTextField() generates a
text input eld for the specied model attribute and changes its CSS class upon any input
error.
If we use the CSS style le form.css provided by the yiic script,the generated formwould
be like the following:
Figure 3.1:The login page
Figure 3.2:The login with error page
Starting fromversion 1.1.1,a new widget called CActiveFormis provided to facilitate form
creation.The widget is capable of supporting seamless and consistent validation on both
client and server sides.Using CActiveForm,the above view code can be rewritten as:
3.5 Collecting Tabular Input 57
<div class="form">
<?php $form=$this->beginWidget('CActiveForm');?>
<?php echo $form->errorSummary($model);?>
<div class="row">
<?php echo $form->label($model,'username');?>
<?php echo $form->textField($model,'username')?>
</div>
<div class="row">
<?php echo $form->label($model,'password');?>
<?php echo $form->passwordField($model,'password')?>
</div>
<div class="row rememberMe">
<?php echo $form->checkBox($model,'rememberMe');?>
<?php echo $form->label($model,'rememberMe');?>
</div>
<div class="row submit">
<?php echo CHtml::submitButton('Login');?>
</div>
<?php $this->endWidget();?>
</div><!-- form -->
3.5 Collecting Tabular Input
Sometimes we want to collect user input in a batch mode.That is,the user can enter
the information for multiple model instances and submit them all at once.We call this
tabular input because the input elds are often presented in an HTML table.
To work with tabular input,we rst need to create or populate an array of model instances,
depending on whether we are inserting or updating the data.We then retrieve the user
input data from the $
POST variable and assign it to each model.A slight dierence from
single model input is that we retrieve the input data using $
POST['ModelClass'][$i]
instead of $
POST['ModelClass'].
public function actionBatchUpdate()
f
//retrieve items to be updated in a batch mode
//assuming each item is of model class'Item'
$items=$this->getItemsToUpdate();
if(isset($
POST['Item']))
f
58 3.Working with Forms
$valid=true;
foreach($items as $i=>$item)
f
if(isset($
POST['Item'][$i]))
$item->attributes=$
POST['Item'][$i];
$valid=$valid && $item->validate();
g
if($valid)//all items are valid
//...do something here
g
//displays the view to collect tabular input
$this->render('batchUpdate',array('items'=>$items));
g
Having the action ready,we need to work on the batchUpdate view to display the input
elds in an HTML table.
<div class="form">
<?php echo CHtml::beginForm();?>
<table>
<tr><th>Name</th><th>Price</th><th>Count</th><th>Description</th></tr>
<?php foreach($items as $i=>$item):?>
<tr>
<td><?php echo CHtml::activeTextField($item,"[$i]name");?></td>
<td><?php echo CHtml::activeTextField($item,"[$i]price");?></td>
<td><?php echo CHtml::activeTextField($item,"[$i]count");?></td>
<td><?php echo CHtml::activeTextArea($item,"[$i]description");?></td>
</tr>
<?php endforeach;?>
</table>
<?php echo CHtml::submitButton('Save');?>
<?php echo CHtml::endForm();?>
</div><!-- form -->
Note in the above that we use"[$i]name"instead of"name"as the second parameter when
calling CHtml::activeTextField.
If there are any validation errors,the corresponding input elds will be highlighted auto-
matically,just like the single model input we described earlier on.
3.6 Using Form Builder
When creating HTML forms,we often nd that we are writing a lot of repetitive view
code which is dicult to be reused in a dierent project.For example,for every input
3.6 Using Form Builder 59
eld,we need to associate it with a text label and display possible validation errors.To
improve the reusability of these code,we can use the form builder feature which has been
available since Yii version 1.1.0.
3.6.1 Basic Concepts
The Yii formbuilder uses a CFormobject to represent the specications needed to describe
an HTML form,including which data models are associated with the form,what kind of
input elds there are in the form,and how to render the whole form.Developers mainly
need to create and congure this CForm object,and then call its rendering method to
display the form.
Form input specications are organized in terms of a form element hierarchy.At the
root of the hierarchy,it is the CForm object.The root form object maintains its chil-
dren in two collections:CForm::buttons and CForm::elements.The former contains the
button elements (such as submit buttons,reset buttons),while the latter contains the
input elements,static text and sub-forms.A sub-form is a CForm object contained
in the CForm::elements collection of another form.It can have its own data model,
CForm::buttons and CForm::elements collections.
When users submit a form,the data entered into the input elds of the whole form hi-
erarchy are submitted,including those input elds that belong to the sub-forms.CForm
provides convenient methods that can automatically assign the input data to the corre-
sponding model attributes and perform data validation.
3.6.2 Creating a Simple Form
In the following,we show how to use the form builder to create a login form.
First,we write the login action code:
public function actionLogin()
f
$model = new LoginForm;
$form = new CForm('application.views.site.loginForm',$model);
if($form->submitted('login') && $form->validate())
$this->redirect(array('site/index'));
else
$this->render('login',array('form'=>$form));
g
In the above code,we create a CFormobject using the specications pointed to by the path
alias application.views.site.loginForm (to be explained shortly).The CForm object is
60 3.Working with Forms
associated with the LoginForm model as described in Creating Model.
As the code reads,if the form is submitted and all inputs are validated without any error,
we would redirect the user browser to the site/index page.Otherwise,we render the
login view with the form.
The path alias application.views.site.loginForm actually refers to the PHPle protected/
views/site/loginForm.php.The le should return a PHP array representing the congu-
ration needed by CForm,as shown in the following:
return array(
'title'=>'Please provide your login credential',
'elements'=>array(
'username'=>array(
'type'=>'text',
'maxlength'=>32,
),
'password'=>array(
'type'=>'password',
'maxlength'=>32,
),
'rememberMe'=>array(
'type'=>'checkbox',
)
),
'buttons'=>array(
'login'=>array(
'type'=>'submit',
'label'=>'Login',
),
),
);
The conguration is an associative array consisting of name-value pairs that are used
to initialize the corresponding properties of CForm.The most important properties to
congure,as we aformentioned,are CForm::elements and CForm::buttons.Each of them
takes an array specifying a list of form elements.We will give more details on how to
congure form elements in the next sub-section.
Finally,we write the login view script,which can be as simple as follows,
<h1>Login</h1>
3.6 Using Form Builder 61
<div class="form">
<?php echo $form;?>
</div>
Tip:The above code echo $form;is equivalent to echo $form->render();.This
is because CForm implements
toString magic method which calls render() and
returns its result as the string representation of the form object.
3.6.3 Specifying Form Elements
Using the form builder,the majority of our eort is shifted from writing view script
code to specifying the form elements.In this sub-section,we describe how to specify
the CForm::elements property.We are not going to describe CForm::buttons because its
conguration is nearly the same as CForm::elements.
The CForm::elements property accepts an array as its value.Each array element species
a single form element which can be an input element,a static text string or a sub-form.
Specifying Input Element
An input element mainly consists of a label,an input eld,a hint text and an error display.
It must be associated with a model attribute.The specication for an input element is
represented as a CFormInputElement instance.The following code in the CForm::elements
array species a single input element:
'username'=>array(
'type'=>'text',
'maxlength'=>32,
),
It states that the model attribute is named as username,and the input eld type is text
whose maxlength attribute is 32.We can specify other options in the above array as long
as they are writable properties of CFormInputElement.For example,we may specify the
hint option in order to display a hint text,or we may specify the items option if the input
eld is a list box,a drop-down list,a check-box list or a radio-button list.
The type option deserves additional attention.It species the type of the input eld to be
rendered.For example,the text type means a normal text input eld should be rendered;
the password type means a password input eld should be rendered.CFormInputElement
recognizes the following built-in types:
62 3.Working with Forms
text
hidden
password
textarea
le
radio
checkbox
listbox
dropdownlist
checkboxlist
radiolist
Besides these built-in types,the type option can also take a widget class name or the path
alias to it.The widget class must extend from CInputWidget.When rendering the input
element,an instance of the specied widget class will be created and rendered.The widget
will be congured using the specication as given for the input element.
Specifying Static Text
In many cases,a formmay contain some decorational HTML code besides the input elds.
For example,a horizontal line may be needed to separate dierent portions of the form;
an image may be needed at certain places to enhance the visual appearance of the form.
We may specify these HTML code as static text in the CForm::elements collection.To do
so,we simply specify a static text string as an array element in the appropriate position
in CForm::elements.For example,
return array(
'elements'=>array(
......
'password'=>array(
'type'=>'password',
'maxlength'=>32,
),
'<hr/>',
3.6 Using Form Builder 63
'rememberMe'=>array(
'type'=>'checkbox',
)
),
......
);
In the above,we insert a horizontal line between the password input and the rememberMe
input.
Static text is best used when the text content and their position are irregular.If each
input element in a form needs to be decorated similarly,we should customize the form
rendering approach,as to be explained shortly in this section.
Specifying Sub-form
Sub-forms are used to divide a lengthy form into several logically connected portions.For
example,we may divide user registration form into two sub-forms:login information and
prole information.Each sub-formmay or may not be associated with a data model.In the
user registration form example,if we store user login information and prole information
in two separate database tables (and thus two data models),then each sub-form would be
associated with a corresponding data model.If we store everything in a single database
table,then neither sub-form has a data model because they share the same model with
the root form.
A sub-form is also represented as a CForm object.In order to specify a sub-form,we
should congure the CForm::elements property with an element whose type is form:
return array(
'elements'=>array(
......
'user'=>array(
'type'=>'form',
'title'=>'Login Credential',
'elements'=>array(
'username'=>array(
'type'=>'text',
),
'password'=>array(
'type'=>'password',
),
'email'=>array(
64 3.Working with Forms
'type'=>'text',
),
),
),
'profile'=>array(
'type'=>'form',
......
),
......
),
......
);
Like conguring a root form,we mainly need to specify the CForm::elements property for
a sub-form.If a sub-form needs to be associated with a data model,we can congure its
CForm::model property as well.
Sometimes,we may want to represent a form using a class other than the default CForm.
For example,as will show shortly in this section,we may extend CForm to customize the
form rendering logic.By specifying the input element type to be form,a sub-form will
automatically be represented as an object whose class is the same as its parent form.If
we specify the input element type to be something like XyzForm (a string terminated with
Form),then the sub-form will be represented as a XyzForm object.
3.6.4 Accessing Form Elements
Accessing form elements is as simple as accessing array elements.The CForm::elements
property returns a CFormElementCollection object,which extends from CMap and allows
accessing its elements like a normal array.For example,in order to access the username
element in the login form example,we can use the following code:
$username = $form->elements['username'];
And to access the email element in the user registration form example,we can use
$email = $form->elements['user']->elements['email'];
Because CForm implements array access for its CForm::elements property,the above code
can be further simplied as:
$username = $form['username'];
$email = $form['user']['email'];
3.6 Using Form Builder 65
3.6.5 Creating a Nested Form
We already described sub-forms.We call a form with sub-forms a nested form.In this
section,we use the user registration form as an example to show how to create a nested
form associated with multiple data models.We assume the user credential information is
stored as a User model,while the user prole information is stored as a Profile model.
We rst create the register action as follows:
public function actionRegister()
f
$form = new CForm('application.views.user.registerForm');
$form['user']->model = new User;
$form['profile']->model = new Profile;
if($form->submitted('register') && $form->validate())
f
$user = $form['user']->model;
$profile = $form['profile']->model;
if($user->save(false))
f
$profile->userID = $user->id;
$profile->save(false);
$this->redirect(array('site/index'));
g
g
$this->render('register',array('form'=>$form));
g
In the above,we create the form using the conguration specied by application.views.
user.registerForm.After the form is submitted and validated successfully,we attempt
to save the user and prole models.We retrieve the user and prole models by accessing
the model property of the corresponding sub-form objects.Because the input validation
is already done,we call $user->save(false) to skip the validation.We do this similarly
for the prole model.
Next,we write the form conguration le protected/views/user/registerForm.php:
return array(
'elements'=>array(
'user'=>array(
'type'=>'form',
'title'=>'Login information',
'elements'=>array(
'username'=>array(
66 3.Working with Forms
'type'=>'text',
),
'password'=>array(
'type'=>'password',
),
'email'=>array(
'type'=>'text',
)
),
),
'profile'=>array(
'type'=>'form',
'title'=>'Profile information',
'elements'=>array(
'firstName'=>array(
'type'=>'text',
),
'lastName'=>array(
'type'=>'text',
),
),
),
),
'buttons'=>array(
'register'=>array(
'type'=>'submit',
'label'=>'Register',
),
),
);
In the above,when specifying each sub-form,we also specify its CForm::title property.
The default form rendering logic will enclose each sub-form in a eld-set which uses this
property as its title.
Finally,we write the simple register view script:
<h1>Register</h1>
<div class="form">
<?php echo $form;?>
</div>
3.6 Using Form Builder 67
3.6.6 Customizing Form Display
The main benet of using formbuilder is the separation of logic (formconguration stored
in a separate le) and presentation (CForm::render method).As a result,we can customize
the form display by either overriding CForm::render or providing a partial view to render
the form.Both approaches can keep the form conguration intact and can be reused
easily.
When overriding CForm::render,one mainly needs to traverse through the CForm::elements
and CForm::buttons collections and call the CFormElement::render method of each form
element.For example,
class MyForm extends CForm
f
public function render()
f
$output = $this->renderBegin();
foreach($this->getElements() as $element)
$output.= $element->render();
$output.= $this->renderEnd();
return $output;
g
g
We may also write a view script
form to render a form:
<?php
echo $form->renderBegin();
foreach($form->getElements() as $element)
echo $element->render();
echo $form->renderEnd();
To use this view script,we can simply call:
<div class="form">
$this->renderPartial('
form',array('form'=>$form));
</div>
68 3.Working with Forms
If a generic form rendering does not work for a particular form (for example,the form
needs some irregular decorations for certain elements),we can do like the following in a
view script:
some complex UI elements here
<?php echo $form['username'];?>
some complex UI elements here
<?php echo $form['password'];?>
some complex UI elements here
In the last approach,the form builder seems not to bring us much benet,as we still
need to write similar amount of form code.It is still benecial,however,that the form is
specied using a separate conguration le as it helps developers to better focus on the
logic.
Chapter 4
Working with Databases
4.1 Working with Database
Yii provides powerful support for database programming.Built on top of the PHP Data
Objects (PDO) extension,Yii Data Access Objects (DAO) enables accessing to dierent
database management systems (DBMS) in a single uniform interface.Applications devel-
oped using Yii DAO can be easily switched to use a dierent DBMS without the need to
modify the data accessing code.Yii Active Record (AR),implemented as a widely adopted
Object-Relational Mapping (ORM) approach,further simplies database programming.
Representing a table in terms of a class and a row an instance,Yii AR eliminates the
repetitive task of writing those SQL statements that mainly deal with CRUD (create,
read,update and delete) operations.
Although Yii DAO and AR can handle nearly all database-related tasks,you can still use
your own database libraries in your Yii application.As a matter of fact,Yii framework is
carefully designed to be used together with other third-party libraries.
4.2 Data Access Objects (DAO)
Data Access Objects (DAO) provides a generic API to access data stored in dierent
database management systems (DBMS).As a result,the underlying DBMS can be changed
to a dierent one without requiring change of the code which uses DAO to access the data.
Yii DAO is built on top of PHP Data Objects (PDO) which is an extension providing
unied data access to many popular DBMS,such as MySQL,PostgreSQL.Therefore,to
use Yii DAO,the PDO extension and the specic PDO database driver (e.g.PDO
MYSQL)
have to be installed.
Yii DAO mainly consists of the following four classes:
CDbConnection:represents a connection to a database.
70 4.Working with Databases
CDbCommand:represents an SQL statement to execute against a database.
CDbDataReader:represents a forward-only stream of rows from a query result set.
CDbTransaction:represents a DB transaction.
In the following,we introduce the usage of Yii DAO in dierent scenarios.
4.2.1 Establishing Database Connection
To establish a database connection,create a CDbConnection instance and activate it.A
data source name (DSN) is needed to specify the information required to connect to the
database.A username and password may also be needed to establish the connection.An
exception will be raised in case an error occurs during establishing the connection (e.g.
bad DSN or invalid username/password).
$connection=new CDbConnection($dsn,$username,$password);
//establish connection.You may try...catch possible exceptions
$connection->active=true;
......
$connection->active=false;//close connection
The format of DSNdepends on the PDOdatabase driver in use.In general,a DSNconsists
of the PDO driver name,followed by a colon,followed by the driver-specic connection
syntax.See PDO documentation for complete information.Below is a list of commonly
used DSN formats:
SQLite:sqlite:/path/to/dbfile
MySQL:mysql:host=localhost;dbname=testdb
PostgreSQL:pgsql:host=localhost;port=5432;dbname=testdb
SQL Server:mssql:host=localhost;dbname=testdb
Oracle:oci:dbname=//localhost:1521/testdb
Because CDbConnection extends from CApplicationComponent,we can also use it as an
application component.To do so,congure in a db (or other name) application component
in the application conguration as follows,
4.2 Data Access Objects (DAO) 71
array(
......
'components'=>array(
......
'db'=>array(
'class'=>'CDbConnection',
'connectionString'=>'mysql:host=localhost;dbname=testdb',
'username'=>'root',
'password'=>'password',
'emulatePrepare'=>true,//needed by some MySQL installations
),
),
)
We can then access the DB connection via Yii::app()->db which is already activated au-
tomatically,unless we explictly congure CDbConnection::autoConnect to be false.Using
this approach,the single DB connection can be shared in multiple places in our code.
4.2.2 Executing SQL Statements
Once a database connection is established,SQL statements can be executed using CDb-
Command.One creates a CDbCommand instance by calling CDbConnection::createCommand()
with the specied SQL statement:
$command=$connection->createCommand($sql);
//if needed,the SQL statement may be updated as follows:
//$command->text=$newSQL;
A SQL statement is executed via CDbCommand in one of the following two ways:
execute():performs a non-query SQL statement,such as INSERT,UPDATE and DELETE.
If successful,it returns the number of rows that are aected by the execution.
query():performs an SQL statement that returns rows of data,such as SELECT.
If successful,it returns a CDbDataReader instance from which one can traverse
the resulting rows of data.For convenience,a set of queryXXX() methods are also
implemented which directly return the query results.
An exception will be raised if an error occurs during the execution of SQL statements.
$rowCount=$command->execute();//execute the non-query SQL
$dataReader=$command->query();//execute a query SQL
72 4.Working with Databases
$rows=$command->queryAll();//query and return all rows of result
$row=$command->queryRow();//query and return the first row of result
$column=$command->queryColumn();//query and return the first column of result
$value=$command->queryScalar();//query and return the first field in the first row
4.2.3 Fetching Query Results
After CDbCommand::query() generates the CDbDataReader instance,one can retrieve
rows of resulting data by calling CDbDataReader::read() repeatedly.One can also use
CDbDataReader in PHP's foreach language construct to retrieve row by row.
$dataReader=$command->query();
//calling read() repeatedly until it returns false
while(($row=$dataReader->read())!==false) f...g
//using foreach to traverse through every row of data
foreach($dataReader as $row) f...g
//retrieving all rows at once in a single array
$rows=$dataReader->readAll();
Note:Unlike query(),all queryXXX() methods return data directly.For example,
queryRow() returns an array representing the rst row of the querying result.
4.2.4 Using Transactions
When an application executes a few queries,each reading and/or writing information in
the database,it is important to be sure that the database is not left with only some of
the queries carried out.A transaction,represented as a CDbTransaction instance in Yii,
may be initiated in this case:
Begin the transaction.
Execute queries one by one.Any updates to the database are not visible to the
outside world.
Commit the transaction.Updates become visible if the transaction is successful.
If one of the queries fails,the entire transaction is rolled back.
The above workow can be implemented using the following code:
4.2 Data Access Objects (DAO) 73
$transaction=$connection->beginTransaction();
try
f
$connection->createCommand($sql1)->execute();
$connection->createCommand($sql2)->execute();
//....other SQL executions
$transaction->commit();
g
catch(Exception $e)//an exception is raised if a query fails
f
$transaction->rollBack();
g
4.2.5 Binding Parameters
To avoid SQL injection attacks and to improve performance of executing repeatedly used
SQL statements,one can"prepare"an SQL statement with optional parameter place-
holders that are to be replaced with the actual parameters during the parameter binding
process.
The parameter placeholders can be either named (represented as unique tokens) or un-
named (represented as question marks).Call CDbCommand::bindParam() or CDbCom-
mand::bindValue() to replace these placeholders with the actual parameters.The param-
eters do not need to be quoted:the underlying database driver does it for you.Parameter
binding must be done before the SQL statement is executed.
//an SQL with two placeholders":username"and":email"
$sql="INSERT INTO tbl
user (username,email) VALUES(:username,:email)";
$command=$connection->createCommand($sql);
//replace the placeholder":username"with the actual username value
$command->bindParam(":username",$username,PDO::PARAM
STR);
//replace the placeholder":email"with the actual email value
$command->bindParam(":email",$email,PDO::PARAM
STR);
$command->execute();
//insert another row with a new set of parameters
$command->bindParam(":username",$username2,PDO::PARAM
STR);
$command->bindParam(":email",$email2,PDO::PARAM
STR);
$command->execute();
The methods bindParam() and bindValue() are very similar.The only dierence is that
the former binds a parameter with a PHP variable reference while the latter with a value.
For parameters that represent large blocks of data memory,the former is preferred for
performance consideration.
For more details about binding parameters,see the relevant PHP documentation.
74 4.Working with Databases
4.2.6 Binding Columns
When fetching query results,one can also bind columns with PHP variables so that they
are automatically populated with the latest data each time a row is fetched.
$sql="SELECT username,email FROM tbl
user";
$dataReader=$connection->createCommand($sql)->query();
//bind the 1st column (username) with the $username variable
$dataReader->bindColumn(1,$username);
//bind the 2nd column (email) with the $email variable
$dataReader->bindColumn(2,$email);
while($dataReader->read()!==false)
f
//$username and $email contain the username and email in the current row
g
4.2.7 Using Table Prex
Starting from version 1.1.0,Yii provides integrated support for using table prex.Ta-
ble prex means a string that is prepended to the names of the tables in the currently
connected database.It is mostly used in a shared hosting environment where multiple
applications share a single database and use dierent table prexes to dierentiate from
each other.For example,one application could use tbl
as prex while the other yii
.
To use table prex,congure the CDbConnection::tablePrex property to be the desired
table prex.Then,in SQL statements use ffTableNamegg to refer to table names,where
TableName means the table name without prex.For example,if the database contains a
table named tbl
user where tbl
is congured as the table prex,then we can use the
following code to query about users:
$sql='SELECT * FROM ffusergg';
$users=$connection->createCommand($sql)->queryAll();
4.3 Active Record
Although Yii DAO can handle virtually any database-related task,chances are that we
would spend 90% of our time in writing some SQL statements which perform the common
CRUD (create,read,update and delete) operations.It is also dicult to maintain our
code when they are mixed with SQL statements.To solve these problems,we can use
Active Record.
Active Record (AR) is a popular Object-Relational Mapping (ORM) technique.Each AR
class represents a database table (or view) whose attributes are represented as the AR
4.3 Active Record 75
class properties,and an AR instance represents a row in that table.Common CRUD
operations are implemented as AR methods.As a result,we can access our data in a more
object-oriented way.For example,we can use the following code to insert a new row to
the tbl
post table:
$post=new Post;
$post->title='sample post';
$post->content='post body content';
$post->save();
In the following we describe how to set up AR and use it to perform CRUD operations.
We will show how to use AR to deal with database relationships in the next section.For
simplicity,we use the following database table for our examples in this section.Note that
if you are using MySQL database,you should replace AUTOINCREMENT with AUTO
INCREMENT
in the following SQL.
CREATE TABLE tbl
post (
id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
title VARCHAR(128) NOT NULL,
content TEXT NOT NULL,
create
time INTEGER NOT NULL
);
Note:AR is not meant to solve all database-related tasks.It is best used for
modeling database tables in PHP constructs and performing queries that do not
involve complex SQLs.Yii DAO should be used for those complex scenarios.
4.3.1 Establishing DB Connection
AR relies on a DB connection to perform DB-related operations.By default,it assumes
that the db application component gives the needed CDbConnection instance which serves
as the DB connection.The following application conguration shows an example:
return array(
'components'=>array(
'db'=>array(
'class'=>'system.db.CDbConnection',
'connectionString'=>'sqlite:path/to/dbfile',
//turn on schema caching to improve performance
//'schemaCachingDuration'=>3600,
),
),
);
76 4.Working with Databases
Tip:Because Active Record relies on the metadata about tables to determine the
column information,it takes time to read the metadata and analyze it.If the schema
of your database is less likely to be changed,you should turn on schema caching
by conguring the CDbConnection::schemaCachingDuration property to be a value
greater than 0.
Support for AR is limited by DBMS.Currently,only the following DBMS are supported:
MySQL 4.1 or later
PostgreSQL 7.3 or later
SQLite 2 and 3
Microsoft SQL Server 2000 or later
Oracle
Note:The support for Microsoft SQL Server has been available since version 1.0.4;
And the support for Oracle has been available since version 1.0.5.
If you want to use an application component other than db,or if you want to work with
multiple databases using AR,you should override CActiveRecord::getDbConnection().
The CActiveRecord class is the base class for all AR classes.
Tip:There are two ways to work with multiple databases in AR.If the schemas of
the databases are dierent,you may create dierent base AR classes with dierent
implementation of getDbConnection().Otherwise,dynamically changing the static
variable CActiveRecord::db is a better idea.
4.3.2 Dening AR Class
To access a database table,we rst need to dene an ARclass by extending CActiveRecord.
Each AR class represents a single database table,and an AR instance represents a row
in that table.The following example shows the minimal code needed for the AR class
representing the tbl
post table.
4.3 Active Record 77
class Post extends CActiveRecord
f
public static function model($className=
CLASS
)
f
return parent::model($className);
g
public function tableName()
f
return'tbl
post';
g
g
Tip:Because AR classes are often referenced in many places,we can import the
whole directory containing the AR class,instead of including them one by one.For
example,if all our AR class les are under protected/models,we can congure the
application as follows:
return array(
'import'=>array(
'application.models.*',
),
);
By default,the name of the AR class is the same as the database table name.Override
the tableName() method if they are dierent.The model() method is declared as such for
every AR class (to be explained shortly).
Info:To use the table prex feature introduced in version 1.1.0,the tableName()
method for an AR class may be overridden as follows,
public function tableName()
f
return'ffpostgg';
g
That is,instead of returning the fully qualied table name,we return the table name
without the prex and enclose it in double curly brackets.
Column values of a table row can be accessed as properties of the corresponding AR
instance.For example,the following code sets the title column (attribute):
$post=new Post;
$post->title='a sample post';
78 4.Working with Databases
Although we never explicitly declare the title property in the Post class,we can still
access it in the above code.This is because title is a column in the tbl
post table,and
CActiveRecord makes it accessible as a property with the help of the PHP
get() magic
method.An exception will be thrown if we attempt to access a non-existing column in
the same way.
Info:In this guide,we use lower case for all table names and column names.
This is because dierent DBMS handle case-sensitivity dierently.For example,
PostgreSQL treats column names as case-insensitive by default,and we must quote
a column in a query condition if the column contains mixed-case letters.Using lower
case would help eliminate this problem.
AR relies on well dened primary keys of tables.If a table does not have a primary key,it
is required that the corresponding AR class specify which column(s) should be the primary
key by overriding the primaryKey() method as follows,
public function primaryKey()
f
return'id';
//For composite primary key,return an array like the following
//return array('pk1','pk2');
g
4.3.3 Creating Record
To insert a new row into a database table,we create a new instance of the corresponding
AR class,set its properties associated with the table columns,and call the save() method
to nish the insertion.
$post=new Post;
$post->title='sample post';
$post->content='content for the sample post';
$post->create
time=time();
$post->save();
If the table's primary key is auto-incremental,after the insertion the AR instance will
contain an updated primary key.In the above example,the id property will reect the
primary key value of the newly inserted post,even though we never change it explicitly.
If a column is dened with some static default value (e.g.a string,a number) in the
table schema,the corresponding property in the AR instance will automatically has such
4.3 Active Record 79
a value after the instance is created.One way to change this default value is by explicitly
declaring the property in the AR class:
class Post extends CActiveRecord
f
public $title='please enter a title';
......
g
$post=new Post;
echo $post->title;//this would display:please enter a title
Starting from version 1.0.2,an attribute can be assigned a value of CDbExpression type
before the record is saved (either insertion or updating) to the database.For example,
in order to save a timestamp returned by the MySQL NOW() function,we can use the
following code:
$post=new Post;
$post->create
time=new CDbExpression('NOW()');
//$post->create
time='NOW()';will not work because
//'NOW()'will be treated as a string
$post->save();
Tip:While AR allows us to perform database operations without writing cumber-
som SQL statements,we often want to know what SQL statements are executed
by AR underneath.This can be achieved by turning on the logging feature of Yii.
For example,we can turn on CWebLogRoute in the application conguration,and
we will see the executed SQL statements being displayed at the end of each Web
page.Since version 1.0.5,we can set CDbConnection::enableParamLogging to be
true in the application conguration so that the parameter values bound to the SQL
statements are also logged.
4.3.4 Reading Record
To read data in a database table,we call one of the find methods as follows.
//find the first row satisfying the specified condition
$post=Post::model()->find($condition,$params);
//find the row with the specified primary key
$post=Post::model()->findByPk($postID,$condition,$params);
//find the row with the specified attribute values
80 4.Working with Databases
$post=Post::model()->findByAttributes($attributes,$condition,$params);
//find the first row using the specified SQL statement
$post=Post::model()->findBySql($sql,$params);
In the above,we call the find method with Post::model().Remember that the static
method model() is required for every AR class.The method returns an AR instance that
is used to access class-level methods (something similar to static class methods) in an
object context.
If the find method nds a row satisfying the query conditions,it will return a Post
instance whose properties contain the corresponding column values of the table row.We
can then read the loaded values like we do with normal object properties,for example,
echo $post->title;.
The find method will return null if nothing can be found in the database with the given
query condition.
When calling find,we use $condition and $params to specify query conditions.Here
$condition can be string representing the WHERE clause in a SQL statement,and $params
is an array of parameters whose values should be bound to the placeholders in $condition.
For example,
//find the row with postID=10
$post=Post::model()->find('postID=:postID',array(':postID'=>10));
Note:In the above,we may need to escape the reference to the postID column for
certain DBMS.For example,if we are using PostgreSQL,we would have to write the
condition as"postID"=:postID,because PostgreSQL by default will treat column
names as case-insensitive.
We can also use $condition to specify more complex query conditions.Instead of a string,
we let $condition be a CDbCriteria instance,which allows us to specify conditions other
than the WHERE clause.For example,
$criteria=new CDbCriteria;
$criteria->select='title';//only select the'title'column
$criteria->condition='postID=:postID';
$criteria->params=array(':postID'=>10);
$post=Post::model()->find($criteria);//$params is not needed
4.3 Active Record 81
Note,when using CDbCriteria as query condition,the $params parameter is no longer
needed since it can be specied in CDbCriteria,as shown above.
An alternative way to CDbCriteria is passing an array to the find method.The array
keys and values correspond to the criteria's property name and value,respectively.The
above example can be rewritten as follows,
$post=Post::model()->find(array(
'select'=>'title',
'condition'=>'postID=:postID',
'params'=>array(':postID'=>10),
));
Info:When a query condition is about matching some columns with the specied
values,we can use ndByAttributes().We let the $attributes parameters be an
array of the values indexed by the column names.In some frameworks,this task can
be achieved by calling methods like findByNameAndTitle.Although this approach
looks attractive,it often causes confusion,conict and issues like case-sensitivity of
column names.
When multiple rows of data matching the specied query condition,we can bring them in
all together using the following findAll methods,each of which has its counterpart find
method,as we already described.
//find all rows satisfying the specified condition
$posts=Post::model()->findAll($condition,$params);
//find all rows with the specified primary keys
$posts=Post::model()->findAllByPk($postIDs,$condition,$params);
//find all rows with the specified attribute values
$posts=Post::model()->findAllByAttributes($attributes,$condition,$params);
//find all rows using the specified SQL statement
$posts=Post::model()->findAllBySql($sql,$params);
If nothing matches the query condition,findAll would return an empty array.This is
dierent from find who would return null if nothing is found.
Besides the find and findAll methods described above,the following methods are also
provided for convenience:
//get the number of rows satisfying the specified condition
$n=Post::model()->count($condition,$params);
82 4.Working with Databases
//get the number of rows using the specified SQL statement
$n=Post::model()->countBySql($sql,$params);
//check if there is at least a row satisfying the specified condition
$exists=Post::model()->exists($condition,$params);
4.3.5 Updating Record
After an AR instance is populated with column values,we can change themand save them
back to the database table.
$post=Post::model()->findByPk(10);
$post->title='new post title';
$post->save();//save the change to database
As we can see,we use the same save() method to perform insertion and updating opera-
tions.If an AR instance is created using the new operator,calling save() would insert a
new row into the database table;if the AR instance is the result of some find or findAll
method call,calling save() would update the existing row in the table.In fact,we can use
CActiveRecord::isNewRecord to tell if an AR instance is new or not.
It is also possible to update one or several rows in a database table without loading them
rst.AR provides the following convenient class-level methods for this purpose:
//update the rows matching the specified condition
Post::model()->updateAll($attributes,$condition,$params);
//update the rows matching the specified condition and primary key(s)
Post::model()->updateByPk($pk,$attributes,$condition,$params);
//update counter columns in the rows satisfying the specified conditions
Post::model()->updateCounters($counters,$condition,$params);
In the above,$attributes is an array of column values indexed by column names;$counters
is an array of incremental values indexed by column names;and $condition and $params
are as described in the previous subsection.
4.3.6 Deleting Record
We can also delete a row of data if an AR instance has been populated with this row.
$post=Post::model()->findByPk(10);//assuming there is a post whose ID is 10
$post->delete();//delete the row from the database table
4.3 Active Record 83
Note,after deletion,the AR instance remains unchanged,but the corresponding row in
the database table is already gone.
The following class-level methods are provided to delete rows without the need of loading
them rst:
//delete the rows matching the specified condition
Post::model()->deleteAll($condition,$params);
//delete the rows matching the specified condition and primary key(s)
Post::model()->deleteByPk($pk,$condition,$params);
4.3.7 Data Validation
When inserting or updating a row,we often need to check if the column values comply to
certain rules.This is especially important if the column values are provided by end users.
In general,we should never trust anything coming from the client side.
AR performs data validation automatically when save() is being invoked.The validation
is based on the rules specied by in the rules() method of the AR class.For more details
about how to specify validation rules,refer to the Declaring Validation Rules section.
Below is the typical workow needed by saving a record:
if($post->save())
f
//data is valid and is successfully inserted/updated
g
else
f
//data is invalid.call getErrors() to retrieve error messages
g
When the data for inserting or updating is submitted by end users in an HTML form,we
need to assign them to the corresponding AR properties.We can do so like the following:
$post->title=$
POST['title'];
$post->content=$
POST['content'];
$post->save();
If there are many columns,we would see a long list of such assignments.This can be
alleviated by making use of the attributes property as shown below.More details can be
found in the Securing Attribute Assignments section and the Creating Action section.
84 4.Working with Databases
//assume $
POST['Post'] is an array of column values indexed by column names
$post->attributes=$
POST['Post'];
$post->save();
4.3.8 Comparing Records
Like table rows,AR instances are uniquely identied by their primary key values.There-
fore,to compare two AR instances,we merely need to compare their primary key val-
ues,assuming they belong to the same AR class.A simpler way is to call CActiveRe-
cord::equals(),however.
Info:Unlike AR implementation in other frameworks,Yii supports composite pri-
mary keys in its AR.A composite primary key consists of two or more columns.
Correspondingly,the primary key value is represented as an array in Yii.The
primaryKey property gives the primary key value of an AR instance.
4.3.9 Customization
CActiveRecord provides a few placeholder methods that can be overridden in child classes
to customize its workow.
beforeValidate and afterValidate:these are invoked before and after validation is
performed.
beforeSave and afterSave:these are invoked before and after saving an AR instance.
beforeDelete and afterDelete:these are invoked before and after an AR instance is
deleted.
afterConstruct:this is invoked for every AR instance created using the new operator.
beforeFind:this is invoked before an AR nder is used to perform a query (e.g.
find(),findAll()).This has been available since version 1.0.9.
afterFind:this is invoked after every AR instance created as a result of query.
4.3.10 Using Transaction with AR
Every AR instance contains a property named dbConnection which is a CDbConnection
instance.We thus can use the transaction feature provided by Yii DAO if it is desired
when working with AR:
4.3 Active Record 85
$model=Post::model();
$transaction=$model->dbConnection->beginTransaction();
try
f
//find and save are two steps which may be intervened by another request
//we therefore use a transaction to ensure consistency and integrity
$post=$model->findByPk(10);
$post->title='new post title';
$post->save();
$transaction->commit();
g
catch(Exception $e)
f
$transaction->rollBack();
g
4.3.11 Named Scopes
Note:The support for named scopes has been available since version 1.0.5.The
original idea of named scopes came from Ruby on Rails.
A named scope represents a named query criteria that can be combined with other named
scopes and applied to an active record query.
Named scopes are mainly declared in the CActiveRecord::scopes() method as name-criteria
pairs.The following code declares two named scopes,published and recently,in the Post
model class:
class Post extends CActiveRecord
f
......
public function scopes()
f
return array(
'published'=>array(
'condition'=>'status=1',
),
'recently'=>array(
'order'=>'create
time DESC',
'limit'=>5,
),
);
g
g
86 4.Working with Databases
Each named scope is declared as an array which can be used to initialize a CDbCriteria
instance.For example,the recently named scope species that the order property to be
create
time DESC and the limit property to be 5,which translates to a query criteria that
should bring back the most recent 5 posts.
Named scopes are mostly used as modiers to the find method calls.Several named scopes
may be chained together and result in a more restrictive query result set.For example,to
nd the recently published posts,we can use the following code:
$posts=Post::model()->published()->recently()->findAll();
In general,named scopes must appear to the left of a find method call.Each of them
provides a query criteria,which is combined with other criterias,including the one passed
to the find method call.The net eect is like adding a list of lters to a query.
Starting from version 1.0.6,named scopes can also be used with update and delete meth-
ods.For example,the following code would delete all recently published posts:
Post::model()->published()->recently()->delete();
Note:Named scopes can only be used with class-level methods.That is,the
method must be called using ClassName::model().
Parameterized Named Scopes
Named scopes can be parameterized.For example,we may want to customize the number
of posts specied by the recently named scope.To do so,instead of declaring the named
scope in the CActiveRecord::scopes method,we need to dene a new method whose name
is the same as the scope name:
public function recently($limit=5)
f
$this->getDbCriteria()->mergeWith(array(
'order'=>'create
time DESC',
'limit'=>$limit,
));
return $this;
g
4.4 Relational Active Record 87
Then,we can use the following statement to retrieve the 3 recently published posts:
$posts=Post::model()->published()->recently(3)->findAll();
If we do not supply the parameter 3 in the above,we would retrieve the 5 recently published
posts by default.
Default Named Scope
A model class can have a default named scope that would be applied for all queries
(including relational ones) about the model.For example,a website supporting multiple
languages may only want to display contents that are in the language the current user spec-
ies.Because there may be many queries about the site contents,we can dene a default
named scope to solve this problem.To do so,we override the CActiveRecord::defaultScope
method as follows,
class Content extends CActiveRecord
f
public function defaultScope()
f
return array(
'condition'=>"language='".Yii::app()->language."'",
);
g
g
Now,if the following method call will automatically use the query criteria as dened above:
$contents=Content::model()->findAll();
Note that default named scope only applies to SELECT queries.It is ignored for INSERT,
UPDATE and DELETE queries.
4.4 Relational Active Record
We have already seen how to use Active Record (AR) to select data froma single database
table.In this section,we describe how to use AR to join several related database tables
and bring back the joint data set.
88 4.Working with Databases
In order to use relational AR,it is recommended that primary-foreign key constraints are
declared for tables that need to be joined.The constraints will help to keep the consistency
and integrity of the relational data.
For simplicity,we will use the database schema shown in the following entity-relationship
(ER) diagram to illustrate examples in this section.
Figure 4.1:ER Diagram
Info:Support for foreign key constraints varies in dierent DBMS.SQLite lt;3.6.19
does not support foreign key constraints,but you can still declare the constraints
when creating tables.
4.4.1 Declaring Relationship
Before we use AR to perform relational query,we need to let AR know how one AR class
is related with another.
Relationship between two AR classes is directly associated with the relationship between
the database tables represented by the AR classes.From database point of view,a rela-
tionship between two tables A and B has three types:one-to-many (e.g.tbl
user and tbl
post),one-to-one (e.g.tbl
user and tbl
profile) and many-to-many (e.g.tbl
category
and tbl
post).In AR,there are four types of relationships:
BELONGS
TO:if the relationship between table A and B is one-to-many,then B belongs
to A (e.g.Post belongs to User);
HAS
MANY:if the relationship between table A and B is one-to-many,then A has many
B (e.g.User has many Post);
4.4 Relational Active Record 89
HAS
ONE:this is special case of HAS
MANY where A has at most one B (e.g.User has
at most one Profile);
MANY
MANY:this corresponds to the many-to-many relationship in database.An as-
sociative table is needed to break a many-to-many relationship into one-to-many
relationships,as most DBMS do not support many-to-many relationship directly.
In our example database schema,the tbl
post
category serves for this purpose.In
AR terminology,we can explain MANY
MANY as the combination of BELONGS
TO and
HAS
MANY.For example,Post belongs to many Category and Category has many Post.
Declaring relationship in AR involves overriding the relations() method of CActiveRecord.
The method returns an array of relationship congurations.Each array element represents
a single relationship with the following format:
'VarName'=>array('RelationType','ClassName','ForeignKey',...additional options)
where VarName is the name of the relationship;RelationType species the type of the
relationship,which can be one of the four constants:self::BELONGS
TO,self::HAS
ONE,
self::HAS
MANY and self::MANY
MANY;ClassName is the name of the AR class related to
this AR class;and ForeignKey species the foreign key(s) involved in the relationship.
Additional options can be specied at the end for each relationship (to be described later).
The following code shows how we declare the relationships for the User and Post classes.
class Post extends CActiveRecord
f
......
public function relations()
f
return array(
'author'=>array(self::BELONGS
TO,'User','author
id'),
'categories'=>array(self::MANY
MANY,'Category',
'tbl
post
category(post
id,category
id)'),
);
g
g
class User extends CActiveRecord
f
......
public function relations()
90 4.Working with Databases
f
return array(
'posts'=>array(self::HAS
MANY,'Post','author
id'),
'profile'=>array(self::HAS
ONE,'Profile','owner
id'),
);
g
g
Info:A foreign key may be composite,consisting of two or more columns.In this
case,we should concatenate the names of the foreign key columns and separate them
with space or comma.For MANY
MANY relationship type,the associative table name
must also be specied in the foreign key.For example,the categories relationship
in Post is specied with the foreign key tbl
post
category(post
id,category
id).
The declaration of relationships in an AR class implicitly adds a property to the class for
each relationship.After a relational query is performed,the corresponding property will
be populated with the related AR instance(s).For example,if $author represents a User
AR instance,we can use $author->posts to access its related Post instances.
4.4.2 Performing Relational Query
The simplest way of performing relational query is by reading a relational property of
an AR instance.If the property is not accessed previously,a relational query will be
initiated,which joins the two related tables and lters with the primary key of the current
AR instance.The query result will be saved to the property as instance(s) of the related
ARclass.This is known as the lazy loading approach,i.e.,the relational query is performed
only when the related objects are initially accessed.The example below shows how to use
this approach:
//retrieve the post whose ID is 10
$post=Post::model()->findByPk(10);
//retrieve the post's author:a relational query will be performed here
$author=$post->author;
Info:If there is no related instance for a relationship,the corresponding property
could be either null or an empty array.For BELONGS
TO and HAS
ONE relationships,
the result is null;for HAS
MANY and MANY
MANY,it is an empty array.Note that the
HAS
MANY and MANY
MANY relationships return arrays of objects,you will need to
loop through the results before trying to access any properties.Otherwise,you may
receive"Trying to get property of non-object"errors.
4.4 Relational Active Record 91
The lazy loading approach is very convenient to use,but it is not ecient in some scenarios.
For example,if we want to access the author information for N posts,using the lazy
approach would involve executing N join queries.We should resort to the so-called eager
loading approach under this circumstance.
The eager loading approach retrieves the related AR instances together with the main AR
instance(s).This is accomplished by using the with() method together with one of the
nd or ndAll methods in AR.For example,
$posts=Post::model()->with('author')->findAll();
The above code will return an array of Post instances.Unlike the lazy approach,the
author property in each Post instance is already populated with the related User instance
before we access the property.Instead of executing a join query for each post,the eager
loading approach brings back all posts together with their authors in a single join query!
We can specify multiple relationship names in the with() method and the eager loading
approach will bring them back all in one shot.For example,the following code will bring
back posts together with their authors and categories:
$posts=Post::model()->with('author','categories')->findAll();
We can also do nested eager loading.Instead of a list of relationship names,we pass in a
hierarchical representation of relationship names to the with() method,like the following,
$posts=Post::model()->with(
'author.profile',
'author.posts',
'categories')->findAll();
The above example will bring back all posts together with their author and categories.It
will also bring back each author's prole and posts.
Starting from version 1.1.0,eager loading may also be executed by specifying the CDbCri-
teria::with property,like the following:
$criteria=new CDbCriteria;
$criteria->with=array(
'author.profile',
'author.posts',
'categories',
);
$posts=Post::model()->findAll($criteria);
92 4.Working with Databases
or
$posts=Post::model()->findAll(array(
'with'=>array(
'author.profile',
'author.posts',
'categories',
)
);
4.4.3 Relational Query Options
We mentioned that additional options can be specied in relationship declaration.These
options,specied as name-value pairs,are used to customize the relational query.They
are summarized as below.
select:a list of columns to be selected for the related AR class.It defaults to
'*',meaning all columns.Column names referenced in this option should be disam-
biguated.
condition:the WHERE clause.It defaults to empty.Column names referenced in this
option should be disambiguated.
params:the parameters to be bound to the generated SQL statement.This should
be given as an array of name-value pairs.This option has been available since version
1.0.3.
on:the ON clause.The condition specied here will be appended to the joining
condition using the AND operator.Column names referenced in this option should be
disambiguated.This option does not apply to MANY
MANY relations.This option has
been available since version 1.0.2.
order:the ORDER BY clause.It defaults to empty.Column names referenced in this
option should be disambiguated.
with:a list of child related objects that should be loaded together with this object.
Be aware that using this option inappropriately may form an innite relation loop.
joinType:type of join for this relationship.It defaults to LEFT OUTER JOIN.
alias:the alias for the table associated with this relationship.This option has been
available since version 1.0.1.It defaults to null,meaning the table alias is the same
as the relation name.
4.4 Relational Active Record 93
together:whether the table associated with this relationship should be forced to join
together with the primary table and other tables.This option is only meaningful for
HAS
M
ANY andMANY
M
ANY relations:Ifthisoptionissetfalse;thetableassociatedwiththeHAS
M
ANY orMANY
M
ANY relationwillbejoinedwiththeprimarytableinaseparateSQLquery;whichmayimprovetheoverallqueryperformancesincelessduplicateddataisreturned:Thedefaultvalueistrue:Formoredetails;seethesection"RelationalQueryPerformance":Thisoptionhasbeenavailablesinceversion1:0:3:join:
theextraJOINclause:Itdefaultstoempty:Thisoptionhasbeenavailablesinceversion1:1:3:
group:the GROUP BY clause.It defaults to empty.Column names referenced in this option
should be disambiguated.
having:the HAVING clause.It defaults to empty.Column names referenced in this option
should be disambiguated.Note:option has been available since version 1.0.1.
index:the name of the column whose values should be used as keys of the array that stores
related objects.Without setting this option,an related object array would use zero-based
integer index.This option can only be set for HAS
MANY and MANY
MANY relations.This
option has been available since version 1.0.7.
In addition,the following options are available for certain relationships during lazy loading:
limit:limit of the rows to be selected.This option does NOT apply to BELONGS
TO
relation.
offset:oset of the rows to be selected.This option does NOT apply to BELONGS
TO
relation.
Below we modify the posts relationship declaration in the User by including some of the
above options:
class User extends CActiveRecord
f
public function relations()
f
return array(
'posts'=>array(self::HAS
MANY,'Post','author
id',
'order'=>'posts.create
time DESC',
'with'=>'categories'),
'profile'=>array(self::HAS
ONE,'Profile','owner
id'),
);
g
g
Now if we access $author->posts,we would obtain the author's posts sorted according to
their creation time in descending order.Each post instance also has its categories loaded.
94 4.Working with Databases
4.4.4 Disambiguating Column Names
When a column name appears in two or more tables being joined together,it needs to be
disambiguated.This is done by prexing the column name with its table's alias name.
In relational AR query,the alias name for the primary table is xed as t,while the alias
name for a relational table is the same as the corresponding relation name by default.
For example,in the following statement,the alias name for Post and Comment is t and
comments,respectively:
$posts=Post::model()->with('comments')->findAll();
Now assume both Post and Comment have a column called create
time indicating the
creation time of a post or comment,and we would like to fetch posts together with their
comments by ordering rst the posts'creation time and then the comments'creation time.
We need to disambiguate the create
time column like the following:
$posts=Post::model()->with('comments')->findAll(array(
'order'=>'t.create
time,comments.create
time'
));
Note:the behavior of column disambiguation has been changed since version 1.1.0.
Previously in version 1.0.x,by default Yii would automatically generate a table
alias for each relational table,and we had to use the prex??.to refer to this
automatically generated alias.Also,in version 1.0.x,the alias name of the primary
table is the table name itself.
4.4.5 Dynamic Relational Query Options
Starting from version 1.0.2,we can use dynamic relational query options in both with()
and the with option.The dynamic options will overwrite existing options as specied in
the relations() method.For example,with the above User model,if we want to use eager
loading approach to bring back posts belonging to an author in ascending order (the order
option in the relation specication is descending order),we can do the following:
User::model()->with(array(
'posts'=>array('order'=>'posts.create
time ASC'),
'profile',
))->findAll();
4.4 Relational Active Record 95
Starting from version 1.0.5,dynamic query options can also be used when using the lazy
loading approach to perform relational query.To do so,we should call a method whose
name is the same as the relation name and pass the dynamic query options as the method
parameter.For example,the following code returns a user's posts whose status is 1:
$user=User::model()->findByPk(1);
$posts=$user->posts(array('condition'=>'status=1'));
4.4.6 Relational Query Performance
As we described above,the eager loading approach is mainly used in the scenario when we
need to access many related objects.It generates a big complex SQL statement by joining
all needed tables.A big SQL statement is preferrable in many cases since it simplies
ltering based on a column in a related table.It may not be ecient in some cases,
however.
Consider an example where we need to nd the latest posts together with their comments.
Assuming each post has 10 comments,using a single big SQL statement,we will bring
back a lot of redundant post data since each post will be repeated for every comment it
has.Now let's try another approach:we rst query for the latest posts,and then query
for their comments.In this new approach,we need to execute two SQL statements.The
benet is that there is no redundancy in the query results.
So which approach is more ecient?There is no absolute answer.Executing a single
big SQL statement may be more ecient because it causes less overhead in DBMS for
yparsing and executing the SQL statements.On the other hand,using the single SQL
statement,we end up with more redundant data and thus need more time to read and
process them.
For this reason,Yii provides the together query option so that we choose between the two
approaches as needed.By default,Yii adopts the rst approach,i.e.,generating a single
SQL statement to perform eager loading.We can set the together option to be false in
the relation declarations so that some of tables are joined in separate SQL statements.
For example,in order to use the second approach to query for the latest posts with their
comments,we can declare the comments relation in Post class as follows,
public function relations()
f
return array(
'comments'=> array(self::HAS
MANY,'Comment','post
id','together'=>false),
);
g
96 4.Working with Databases
We can also dynamically set this option when we perform the eager loading:
$posts = Post::model()->with(array('comments'=>array('together'=>false)))->findAll();
Note:In version 1.0.x,the default behavior is that Yii will generate and execute
N+1 SQL statements if there are N HAS
MANY or MANY
MANY relations.Each HAS
MANY or MANY
MANY relation has its own SQL statement.By calling the together()
method after with(),we can enforce only a single SQL statement is generated and
executed.For example,
$posts=Post::model()->with(
'author.profile',
'author.posts',
'categories')->together()->findAll();
4.4.7 Statistical Query
Note:Statistical query has been supported since version 1.0.4.
Besides the relational query described above,Yii also supports the so-called statistical
query (or aggregational query).It refers to retrieving the aggregational information about
the related objects,such as the number of comments for each post,the average rating for
each product,etc.Statistical query can only be performed for objects related in HAS
MANY
(e.g.a post has many comments) or MANY
MANY (e.g.a post belongs to many categories
and a category has many posts).
Performing statistical query is very similar to performing relation query as we described
before.We rst need to declare the statistical query in the relations() method of CAc-
tiveRecord like we do with relational query.
class Post extends CActiveRecord
f
public function relations()
f
return array(
'commentCount'=>array(self::STAT,'Comment','post
id'),
'categoryCount'=>array(self::STAT,'Category','post
category(post
id,category
id)'),
);
g
g
4.4 Relational Active Record 97
In the above,we declare two statistical queries:commentCount calculates the number of
comments belonging to a post,and categoryCount calculates the number of categories
that a post belongs to.Note that the relationship between Post and Comment is HAS
MANY,
while the relationship between Post and Category is MANY
MANY (with the joining table post
category).As we can see,the declaration is very similar to those relations we described
in earlier subsections.The only dierence is that the relation type is STAT here.
With the above declaration,we can retrieve the number of comments for a post using
the expression $post->commentCount.When we access this property for the rst time,
a SQL statement will be executed implicitly to retrieve the corresponding result.As we
already know,this is the so-called lazy loading approach.We can also use the eager loading
approach if we need to determine the comment count for multiple posts:
$posts=Post::model()->with('commentCount','categoryCount')->findAll();
The above statement will execute three SQLs to bring back all posts together with their
comment counts and category counts.Using the lazy loading approach,we would end up
with 2*N+1 SQL queries if there are N posts.
By default,a statistical query will calculate the COUNT expression (and thus the comment
count and category count in the above example).We can customize it by specifying
additional options when we declare it in relations().The available options are summarized
as below.
select:the statistical expression.Defaults to COUNT(*),meaning the count of child
objects.
defaultValue:the value to be assigned to those records that do not receive a statisti-
cal query result.For example,if a post does not have any comments,its commentCount
would receive this value.The default value for this option is 0.
condition:the WHERE clause.It defaults to empty.
params:the parameters to be bound to the generated SQL statement.This should
be given as an array of name-value pairs.
order:the ORDER BY clause.It defaults to empty.
group:the GROUP BY clause.It defaults to empty.
having:the HAVING clause.It defaults to empty.
98 4.Working with Databases
4.4.8 Relational Query with Named Scopes
Note:The support for named scopes has been available since version 1.0.5.
Relational query can also be performed in combination with named scopes.It comes in
two forms.In the rst form,named scopes are applied to the main model.In the second
form,named scopes are applied to the related models.
The following code shows how to apply named scopes to the main model.
$posts=Post::model()->published()->recently()->with('comments')->findAll();
This is very similar to non-relational queries.The only dierence is that we have the
with() call after the named-scope chain.This query would bring back recently published
posts together with their comments.
And the following code shows how to apply named scopes to the related models.
$posts=Post::model()->with('comments:recently:approved')->findAll();
The above query will bring back all posts together with their approved comments.Note
that comments refers to the relation name,while recently and approved refer to two named
scopes declared in the Comment model class.The relation name and the named scopes
should be separated by colons.
Named scopes can also be specied in the with option of the relational rules declared in
CActiveRecord::relations().In the following example,if we access $user->posts,it would
bring back all approved comments of the posts.
class User extends CActiveRecord
f
public function relations()
f
return array(
'posts'=>array(self::HAS
MANY,'Post','author
id',
'with'=>'comments:approved'),
);
g
g
4.4 Relational Active Record 99
Note:Named scopes applied to related models must be specied in CActiveRe-
cord::scopes.As a result,they cannot be parameterized.
100 4.Working with Databases
Chapter 5
Caching
5.1 Caching
Caching is a cheap and eective way to improve the performance of a Web application.
By storing relatively static data in cache and serving it from cache when requested,we
save the time needed to generate the data.
Using cache in Yii mainly involves conguring and accessing a cache application com-
ponent.The following application conguration species a cache component that uses
memcache with two cache servers.
array(
......
'components'=>array(
......
'cache'=>array(
'class'=>'system.caching.CMemCache',
'servers'=>array(
array('host'=>'server1','port'=>11211,'weight'=>60),
array('host'=>'server2','port'=>11211,'weight'=>40),
),
),
),
);
When the application is running,the cache component can be accessed via Yii::app()->cache.
Yii provides various cache components that can store cached data in dierent media.For
example,the CMemCache component encapsulates the PHP memcache extension and
uses memory as the medium of cache storage;the CApcCache component encapsulates
the PHP APC extension;and the CDbCache component stores cached data in database.
The following is a summary of the available cache components:
CMemCache:uses PHP memcache extension.
102 5.Caching
CApcCache:uses PHP APC extension.
CXCache:uses PHP XCache extension.Note,this has been available since version
1.0.1.
CEAcceleratorCache:uses PHP EAccelerator extension.
CDbCache:uses a database table to store cached data.By default,it will create
and use a SQLite3 database under the runtime directory.You can explicitly specify
a database for it to use by setting its connectionID property.
CZendDataCache:uses Zend Data Cache as the underlying caching medium.Note,
this has been available since version 1.0.4.
CFileCache:uses les to store cached data.This is particular suitable to cache large
chunk of data (such as pages).Note that this has been available since version 1.0.6.
CDummyCache:presents dummy cache that does no caching at all.The purpose of
this component is to simplify the code that needs to check the availability of cache.
For example,during development or if the server doesn't have actual cache support,
we can use this cache component.When an actual cache support is enabled,we
can switch to use the corresponding cache component.In both cases,we can use
the same code Yii::app()->cache->get($key) to attempt retrieving a piece of data
without worrying that Yii::app()->cache might be null.This component has been
available since version 1.0.5.
Tip:Because all these cache components extend from the same base class CCache,
one can switch to use a dierent type of cache without modifying the code that uses
cache.
Caching can be used at dierent levels.At the lowest level,we use cache to store a single
piece of data,such as a variable,and we call this data caching.At the next level,we store
in cache a page fragment which is generated by a portion of a view script.And at the
highest level,we store a whole page in cache and serve it from cache as needed.
In the next few subsections,we elaborate how to use cache at these levels.
Note:By denition,cache is a volatile storage medium.It does not ensure the
existence of the cached data even if it does not expire.Therefore,do not use cache
as a persistent storage (e.g.do not use cache to store session data).
5.2 Data Caching 103
5.2 Data Caching
Data caching is about storing some PHP variable in cache and retrieving it later from
cache.For this purpose,the cache component base class CCache provides two methods
that are used most of the time:set() and get().
To store a variable $value in cache,we choose a unique ID and call set() to store it:
Yii::app()->cache->set($id,$value);
The cached data will remain in the cache forever unless it is removed because of some
caching policy (e.g.caching space is full and the oldest data are removed).To change this
behavior,we can also supply an expiration parameter when calling set() so that the data
will be removed from the cache after a certain period of time:
//keep the value in cache for at most 30 seconds
Yii::app()->cache->set($id,$value,30);
Later when we need to access this variable (in either the same or a dierent Web request),
we call get() with the ID to retrieve it from cache.If the value returned is false,it means
the value is not available in cache and we should regenerate it.
$value=Yii::app()->cache->get($id);
if($value===false)
f
//regenerate $value because it is not found in cache
//and save it in cache for later use:
//Yii::app()->cache->set($id,$value);
g
When choosing the ID for a variable to be cached,make sure the ID is unique among
all other variables that may be cached in the application.It is NOT required that the
ID is unique across applications because the cache component is intelligent enough to
dierentiate IDs for dierent applications.
Some cache storages,such as MemCache,APC,support retrieving multiple cached values
in a batch mode,which may reduce the overhead involved in retrieving cached data.
Starting fromversion 1.0.8,a new method named mget() is provided to exploit this feature.
In case the underlying cache storage does not support this feature,mget() will still simulate
it.
104 5.Caching
To remove a cached value from cache,call delete();and to remove everything from cache,
callush().Be very careful when callingush() because it also removes cached data that
are from other applications.
Tip:Because CCache implements ArrayAccess,a cache component can be used
liked an array.The followings are some examples:
$cache=Yii::app()->cache;
$cache['var1']=$value1;//equivalent to:$cache->set('var1',$value1);
$value2=$cache['var2'];//equivalent to:$value2=$cache->get('var2');
5.2.1 Cache Dependency
Besides expiration setting,cached data may also be invalidated according to some depen-
dency changes.For example,if we are caching the content of some le and the le is
changed,we should invalidate the cached copy and read the latest content from the le
instead of the cache.
We represent a dependency as an instance of CCacheDependency or its child class.We
pass the dependency instance along with the data to be cached when calling set().
//the value will expire in 30 seconds
//it may also be invalidated earlier if the dependent file is changed
Yii::app()->cache->set($id,$value,30,new CFileCacheDependency('FileName'));
Now if we retrieve $value from cache by calling get(),the dependency will be evaluated
and if it is changed,we will get a false value,indicating the data needs to be regenerated.
Below is a summary of the available cache dependencies:
CFileCacheDependency:the dependency is changed if the le's last modication
time is changed.
CDirectoryCacheDependency:the dependency is changed if any of the les under
the directory and its subdirectories is changed.
CDbCacheDependency:the dependency is changed if the query result of the specied
SQL statement is changed.
CGlobalStateCacheDependency:the dependency is changed if the value of the spec-
ied global state is changed.A global state is a variable that is persistent across
multiple requests and multiple sessions in an application.It is dened via CAppli-
cation::setGlobalState().
5.3 Fragment Caching 105
CChainedCacheDependency:the dependency is changed if any of the dependencies
on the chain is changed.
CExpressionDependency:the dependency is changed if the result of the specied
PHP expression is changed.This class has been available since version 1.0.4.
5.3 Fragment Caching
Fragment caching refers to caching a fragment of a page.For example,if a page displays
a summary of yearly sale in a table,we can store this table in cache to eliminate the time
needed to generate it for each request.
To use fragment caching,we call CController::beginCache() and CController::endCache()
in a controller's view script.The two methods mark the beginning and the end of the page
content that should be cached,respectively.Like data caching,we need an ID to identify
the fragment being cached.
...other HTML content...
<?php if($this->beginCache($id)) f?>
...content to be cached...
<?php $this->endCache();g?>
...other HTML content...
In the above,if beginCache() returns false,the cached content will be automatically in-
serted at the place;otherwise,the content inside the if-statement will be executed and
be cached when endCache() is invoked.
5.3.1 Caching Options
When calling beginCache(),we can supply an array as the second parameter consisting
of caching options to customize the fragment caching.As a matter of fact,the begin-
Cache() and endCache() methods are a convenient wrapper of the COutputCache widget.
Therefore,the caching options can be initial values for any properties of COutputCache.
Duration
Perhaps the most commonly option is duration which species how long the content can
remain valid in cache.It is similar to the expiration parameter of CCache::set().The
following code caches the content fragment for at most one hour:
...other HTML content...
106 5.Caching
<?php if($this->beginCache($id,array('duration'=>3600))) f?>
...content to be cached...
<?php $this->endCache();g?>
...other HTML content...
If we do not set the duration,it would default to 60,meaning the cached content will be
invalidated after 60 seconds.
Dependency
Like data caching,content fragment being cached can also have dependencies.For exam-
ple,the content of a post being displayed depends on whether or not the post is modied.
To specify a dependency,we set the dependency option,which can be either an object
implementing ICacheDependency or a conguration array that can be used to generate
the dependency object.The following code species the fragment content depends on the
change of lastModified column value:
...other HTML content...
<?php if($this->beginCache($id,array('dependency'=>array(
'class'=>'system.caching.dependencies.CDbCacheDependency',
'sql'=>'SELECT MAX(lastModified) FROM Post')))) f?>
...content to be cached...
<?php $this->endCache();g?>
...other HTML content...
Variation
Content being cached may be variated according to some parameters.For example,the
personal prole may look dierently to dierent users.To cache the prole content,we
would like the cached copy to be variated according to user IDs.This essentially means
that we should use dierent IDs when calling beginCache().
Instead of asking developers to variate the IDs according to some scheme,COutputCache
is built-in with such a feature.Below is a summary.
varyByRoute:by setting this option to true,the cached content will be variated
according to route.Therefore,each combination of the requested controller and
action will have a separate cached content.
5.3 Fragment Caching 107
varyBySession:by setting this option to true,we can make the cached content to
be variated according to session IDs.Therefore,each user session may see dierent
content and they are all served from cache.
varyByParam:by setting this option to an array of names,we can make the cached
content to be variated according to the values of the specied GET parameters.For
example,if a page displays the content of a post according to the id GET parameter,
we can specify varyByParam to be array('id') so that we can cache the content for
each post.Without such variation,we would only be able to cache a single post.
varyByExpression:by setting this option to a PHP expression,we can make the
cached content to be variated according to the result of this PHP expression.This
option has been available since version 1.0.4.
Request Types
Sometimes we want the fragment caching to be enabled only for certain types of request.
For example,for a page displaying a form,we only want to cache the form when it is
initially requested (via GET request).Any subsequent display (via POST request) of the
form should not be cached because the form may contain user input.To do so,we can
specify the requestTypes option:
...other HTML content...
<?php if($this->beginCache($id,array('requestTypes'=>array('GET')))) f?>
...content to be cached...
<?php $this->endCache();g?>
...other HTML content...
5.3.2 Nested Caching
Fragment caching can be nested.That is,a cached fragment is enclosed within a bigger
fragment that is also cached.For example,the comments are cached in an inner fragment
cache,and they are cached together with the post content in an outer fragment cache.
...other HTML content...
<?php if($this->beginCache($id1)) f?>
...outer content to be cached...
<?php if($this->beginCache($id2)) f?>
...inner content to be cached...
<?php $this->endCache();g?>
...outer content to be cached...
<?php $this->endCache();g?>
...other HTML content...
108 5.Caching
Dierent caching options can be set to the nested caches.For example,the inner cache
and the outer cache in the above example can be set with dierent duration values.When
the data cached in the outer cache is invalidated,the inner cache may still provide valid
inner fragment.However,it is not true vice versa.If the outer cache contains valid data,
it will always provide the cached copy,even though the content in the inner cache already
expires.
5.4 Page Caching
Page caching refers to caching the content of a whole page.Page caching can occur at
dierent places.For example,by choosing an appropriate page header,the client browser
may cache the page being viewed for a limited time.The Web application itself can also
store the page content in cache.In this subsection,we focus on this latter approach.
Page caching can be considered as a special case of fragment caching.Because the content
of a page is often generated by applying a layout to a view,it will not work if we simply call
beginCache() and endCache() in the layout.The reason is because the layout is applied
within the CController::render() method AFTER the content view is evaluated.
To cache a whole page,we should skip the execution of the action generating the page
content.We can use COutputCache as an action lter to accomplish this task.The
following code shows how we congure the cache lter:
public function filters()
f
return array(
array(
'COutputCache',
'duration'=>100,
'varyByParam'=>array('id'),
),
);
g
The above lter conguration would make the lter to be applied to all actions in the
controller.We may limit it to one or a few actions only by using the plus operator.More
details can be found in lter.
5.5 Dynamic Content 109
Tip:We can use COutputCache as a lter because it extends from CFilterWidget,
which means it is both a widget and a lter.In fact,the way a widget works is
very similar to a lter:a widget (lter) begins before any enclosed content (ac-
tion) is evaluated,and the widget (lter) ends after the enclosed content (action) is
evaluated.
5.5 Dynamic Content
When using fragment caching or page caching,we often encounter the situation where the
whole portion of the output is relatively static except at one or several places.For example,
a help page may display static help information with the name of the user currently logged
in displayed at the top.
To solve this issue,we can variate the cache content according to the username,but
this would be a big waste of our precious cache space since most content are the same
except the username.We can also divide the page into several fragments and cache them
individually,but this complicates our view and makes our code very complex.A better
approach is to use the dynamic content feature provided by CController.
A dynamic content means a fragment of output that should not be cached even if it is
enclosed within a fragment cache.To make the content dynamic all the time,it has to
be generated every time even when the enclosing content is being served from cache.For
this reason,we require that dynamic content be generated by some method or function.
We call CController::renderDynamic() to insert dynamic content at the desired place.
...other HTML content...
<?php if($this->beginCache($id)) f?>
...fragment content to be cached...
<?php $this->renderDynamic($callback);?>
...fragment content to be cached...
<?php $this->endCache();g?>
...other HTML content...
In the above,$callback refers to a valid PHP callback.It can be a string referring to
the name of a method in the current controller class or a global function.It can also be
an array referring to a class method.Any additional parameters to renderDynamic() will
be passed to the callback.The callback should return the dynamic content instead of
displaying it.
110 5.Caching
Chapter 6
Extending Yii
6.1 Overview
Extending Yii is a common activity during development.For example,when you write a
new controller,you extend Yii by inheriting its CController class;when you write a new
widget,you are extending CWidget or an existing widget class.If the extended code is
designed to be reused by third-party developers,we call it an extension.
An extension usually serves for a single purpose.In Yii's terms,it can be classied as
follows,
application component
behavior
widget
controller
action
lter
console command
validator:a validator is a component class extending CValidator.
helper:a helper is a class with only static methods.It is like global functions using
the class name as their namespace.
module:a module is a self-contained software unit that consists of models,views,
controllers and other supporting components.In many aspects,a module resembles
to an application.The main dierence is that a module is inside an application.For
example,we could have a module that provides user management functionalities.
112 6.Extending Yii
An extension can also be a component that does not fall into any of the above categories.
As a matter of fact,Yii is carefully designed such that nearly every piece of its code can
be extended and customized to t for individual needs.
6.2 Using Extensions
Using an extension usually involves the following three steps:
1.Download the extension from Yii's extension repository.
2.Unpack the extension under the extensions/xyz subdirectory of application base
directory,where xyz is the name of the extension.
3.Import,congure and use the extension.
Each extension has a name that uniquely identies it among all extensions.Given an
extension named as xyz,we can always use the path alias ext.xyz to locate its base
directory which contains all les of xyz.
Note:The root path alias ext has been available since version 1.0.8.Previously,
we would need to use application.extensions to refer to the directory containing
all extensions.In the following description,we assume ext is dened.You will need
to replace it with application.extensions if you are using version 1.0.7 or lower.
Dierent extensions have dierent requirements about importing,conguration and usage.
In the following,we summarize common usage scenarios about extensions,according to
their categorization described in the overview.
6.2.1 Zii Extensions
Before we start describing the usage of third-party extensions,we would like to introduce
the Zii extension library,which is a set of extensions developed by the Yii developer team
and included in every release since Yii version 1.1.0.The Zii library is hosted as a Google
project called zii.
When using a Zii extension,one must refer to the corresponding class using a path alias in
the form of zii.path.to.ClassName.Here the root alias zii is predened by Yii.It refers
to the root directory of the Zii library.For example,to use CGridView,we would use the
following code in a view script when referring to the extension:
6.2 Using Extensions 113
$this->widget('zii.widgets.grid.CGridView',array(
'dataProvider'=>$dataProvider,
));
6.2.2 Application Component
To use an application component,we rst need to change the application conguration by
adding a new entry to its components property,like the following:
return array(
//'preload'=>array('xyz',...),
'components'=>array(
'xyz'=>array(
'class'=>'ext.xyz.XyzClass',
'property1'=>'value1',
'property2'=>'value2',
),
//other component configurations
),
);
Then,we can access the component at any place using Yii::app()->xyz.The component
will be lazily created (that is,created when it is accessed for the rst time) unless we list
it the preload property.
6.2.3 Behavior
Behavior can be used in all sorts of components.Its usage involves two steps.In the rst
step,a behavior is attached to a target component.In the second step,a behavior method
is called via the target component.For example:
//$name uniquely identifies the behavior in the component
$component->attachBehavior($name,$behavior);
//test() is a method of $behavior
$component->test();
More often,a behavior is attached to a component using a congurative way instead of
calling the attachBehavior method.For example,to attach a behavior to an application
component,we could use the following application conguration:
return array(
'components'=>array(
114 6.Extending Yii
'db'=>array(
'class'=>'CDbConnection',
'behaviors'=>array(
'xyz'=>array(
'class'=>'ext.xyz.XyzBehavior',
'property1'=>'value1',
'property2'=>'value2',
),
),
),
//....
),
);
The above code attaches the xyz behavior to the db application component.We can do
so because CApplicationComponent denes a property named behaviors.By setting this
property with a list of behavior congurations,the component will attach the correspond-
ing behaviors when it is being initialized.
For CController,CFormModel and CActiveRecord classes which usually need to be ex-
tended,attaching behaviors can be done by overriding their behaviors() method.The
classes will automatically attach any behaviors declared in this method during initializa-
tion.For example,
public function behaviors()
f
return array(
'xyz'=>array(
'class'=>'ext.xyz.XyzBehavior',
'property1'=>'value1',
'property2'=>'value2',
),
);
g
6.2.4 Widget
Widgets are mainly used in views.Given a widget class XyzClass belonging to the xyz
extension,we can use it in a view as follows,
//widget that does not need body content
<?php $this->widget('ext.xyz.XyzClass',array(
'property1'=>'value1',
'property2'=>'value2'));?>
6.2 Using Extensions 115
//widget that can contain body content
<?php $this->beginWidget('ext.xyz.XyzClass',array(
'property1'=>'value1',
'property2'=>'value2'));?>
...body content of the widget...
<?php $this->endWidget();?>
6.2.5 Action
Actions are used by a controller to respond specic user requests.Given an action
class XyzClass belonging to the xyz extension,we can use it by overriding the CCon-
troller::actions method in our controller class:
class TestController extends CController
f
public function actions()
f
return array(
'xyz'=>array(
'class'=>'ext.xyz.XyzClass',
'property1'=>'value1',
'property2'=>'value2',
),
//other actions
);
g
g
Then,the action can be accessed via route test/xyz.
6.2.6 Filter
Filters are also used by a controller.Their mainly pre- and post-process the user re-
quest when it is handled by an action.Given a lter class XyzClass belonging to the xyz
extension,we can use it by overriding the CController::lters method in our controller
class:
class TestController extends CController
f
public function filters()
f
return array(
116 6.Extending Yii
array(
'ext.xyz.XyzClass',
'property1'=>'value1',
'property2'=>'value2',
),
//other filters
);
g
g
In the above,we can use plus and minus operators in the rst array element to apply
the lter to limited actions only.For more details,please refer to the documentation of
CController.
6.2.7 Controller
A controller provides a set of actions that can be requested by users.In order to use a
controller extension,we need to congure the CWebApplication::controllerMap property
in the application conguration:
return array(
'controllerMap'=>array(
'xyz'=>array(
'class'=>'ext.xyz.XyzClass',
'property1'=>'value1',
'property2'=>'value2',
),
//other controllers
),
);
Then,an action a in the controller can be accessed via route xyz/a.
6.2.8 Validator
A validator is mainly used in a model class (one that extends from either CFormModel or
CActiveRecord).Given a validator class XyzClass belonging to the xyz extension,we can
use it by overriding the CModel::rules method in our model class:
class MyModel extends CActiveRecord//or CFormModel
f
public function rules()
f
6.2 Using Extensions 117
return array(
array(
'attr1,attr2',
'ext.xyz.XyzClass',
'property1'=>'value1',
'property2'=>'value2',
),
//other validation rules
);
g
g
6.2.9 Console Command
Aconsole command extension usually enhances the yiic tool with an additional command.
Given a console command XyzClass belonging to the xyz extension,we can use it by
conguring the conguration for the console application:
return array(
'commandMap'=>array(
'xyz'=>array(
'class'=>'ext.xyz.XyzClass',
'property1'=>'value1',
'property2'=>'value2',
),
//other commands
),
);
Then,we can use the yiic tool is equipped with an additional command xyz.
Note:A console application usually uses a conguration le that is dierent from
the one used by a Web application.If an application is created using yiic webapp
command,then the conguration le for the console application protected/yiic
is protected/config/console.php,while the conguration le for the Web appli-
cation is protected/config/main.php.
6.2.10 Module
Please refer to the section about modules on how to use a module.
6.2.11 Generic Component
To use a generic component,we rst need to include its class le by using
118 6.Extending Yii
Yii::import('ext.xyz.XyzClass');
Then,we can either create an instance of the class,congure its properties,and call its
methods.We may also extend it to create new child classes.
6.3 Creating Extensions
Because an extension is meant to be used by third-party developers,it takes some addi-
tional eorts to create it.The followings are some general guidelines:
An extension should be self-contained.That is,its external dependency should be
minimal.It would be a headache for its users if an extension requires installation of
additional packages,classes or resource les.
Files belonging to an extension should be organized under the same directory whose
name is the extension name
Classes in an extension should be prexed with some letter(s) to avoid naming
conict with classes in other extensions.
An extension should come with detailed installation and API documentation.This
would reduce the time and eort needed by other developers when they use the
extension.
An extension should be using an appropriate license.If you want to make your ex-
tension to be used by both open-source and closed-source projects,you may consider
using licenses such as BSD,MIT,etc.,but not GPL as it requires its derived code
to be open-source as well.
In the following,we describe how to create a new extension,according to its categorization
as described in overview.These descriptions also apply when you are creating a component
mainly used in your own projects.
6.3.1 Application Component
An application component should implement the interface IApplicationComponent or ex-
tend from CApplicationComponent.The main method needed to be implemented is IAp-
plicationComponent::init in which the component performs some initialization work.This
method is invoked after the component is created and the initial property values (specied
in application conguration) are applied.
6.3 Creating Extensions 119
By default,an application component is created and initialized only when it is accessed for
the rst time during request handling.If an application component needs to be created
right after the application instance is created,it should require the user to list its ID in
the CApplication::preload property.
6.3.2 Behavior
To create a behavior,one must implement the IBehavior interface.For convenience,Yii
provides a base class CBehavior that already implements this interface and provides some
additional convenient methods.Child classes mainly need to implement the extra methods
that they intend to make available to the components being attached to.
When developing behaviors for CModel and CActiveRecord,one can also extend CMod-
elBehavior and CActiveRecordBehavior,respectively.These base classes oer additional
features that are specically made for CModel and CActiveRecord.For example,the
CActiveRecordBehavior class implements a set of methods to respond to the life cycle
events raised in an ActiveRecord object.A child class can thus override these methods to
put in customized code which will participate in the AR life cycles.
The following code shows an example of an ActiveRecord behavior.When this behavior
is attached to an AR object and when the AR object is being saved by calling save(),
it will automatically sets the create
time and update
time attributes with the current
timestamp.
class TimestampBehavior extends CActiveRecordBehavior
f
public function beforeSave($event)
f
if($this->owner->isNewRecord)
$this->owner->create
time=time();
else
$this->owner->update
time=time();
g
g
6.3.3 Widget
A widget should extend from CWidget or its child classes.
The easiest way of creating a new widget is extending an existing widget and overriding
its methods or changing its default property values.For example,if you want to use a
nicer CSS style for CTabView,you could congure its CTabView::cssFile property when
using the widget.You can also extend CTabView as follows so that you no longer need to
120 6.Extending Yii
congure the property when using the widget.
class MyTabView extends CTabView
f
public function init()
f
if($this->cssFile===null)
f
$file=dirname(
FILE
).DIRECTORY
SEPARATOR.'tabview.css';
$this->cssFile=Yii::app()->getAssetManager()->publish($file);
g
parent::init();
g
g
In the above,we override the CWidget::init method and assign to CTabView::cssFile the
URL to our new default CSS style if the property is not set.We put the new CSS style le
under the same directory containing the MyTabView class le so that they can be packaged
as an extension.Because the CSS style le is not Web accessible,we need to publish as
an asset.
To create a new widget from scratch,we mainly need to implement two methods:CWid-
get::init and CWidget::run.The rst method is called when we use $this->beginWidget to
insert a widget in a view,and the second method is called when we call $this->endWidget.
If we want to capture and process the content displayed between these two method invo-
cations,we can start output buering in CWidget::init and retrieve the buered output
in CWidget::run for further processing.
A widget often involves including CSS,JavaScript or other resource les in the page that
uses the widget.We call these les assets because they stay together with the widget
class le and are usually not accessible by Web users.In order to make these les Web
accessible,we need to publish them using CWebApplication::assetManager,as shown in
the above code snippet.Besides,if we want to include a CSS or JavaScript le in the
current page,we need to register it using CClientScript:
class MyWidget extends CWidget
f
protected function registerClientScript()
f
//...publish CSS or JavaScript file here...
$cs=Yii::app()->clientScript;
$cs->registerCssFile($cssFile);
$cs->registerScriptFile($jsFile);
g
6.3 Creating Extensions 121
g
A widget may also have its own view les.If so,create a directory named views under the
directory containing the widget class le,and put all the view les there.In the widget
class,in order to render a widget view,use $this->render('ViewName'),which is similar
to what we do in a controller.
6.3.4 Action
An action should extend from CAction or its child classes.The main method that needs
to be implemented for an action is IAction::run.
6.3.5 Filter
A lter should extend from CFilter or its child classes.The main methods that need to
be implemented for a lter are CFilter::preFilter and CFilter::postFilter.The former is
invoked before the action is executed while the latter after.
class MyFilter extends CFilter
f
protected function preFilter($filterChain)
f
//logic being applied before the action is executed
return true;//false if the action should not be executed
g
protected function postFilter($filterChain)
f
//logic being applied after the action is executed
g
g
The parameter $filterChain is of type CFilterChain which contains information about
the action that is currently ltered.
6.3.6 Controller
A controller distributed as an extension should extend from CExtController,instead of
CController.The main reason is because CController assumes the controller view les
are located under application.views.ControllerID,while CExtController assumes the
view les are located under the views directory which is a subdirectory of the directory
containing the controller class le.Therefore,it is easier to redistribute the controller
since its view les are staying together with the controller class le.
122 6.Extending Yii
6.3.7 Validator
Avalidator should extend fromCValidator and implement its CValidator::validateAttribute
method.
class MyValidator extends CValidator
f
protected function validateAttribute($model,$attribute)
f
$value=$model->$attribute;
if($value has error)
$model->addError($attribute,$errorMessage);
g
g
6.3.8 Console Command
Aconsole command should extend fromCConsoleCommand and implement its CConsoleCom-
mand::run method.Optionally,we can override CConsoleCommand::getHelp to provide
some nice help information about the command.
class MyCommand extends CConsoleCommand
f
public function run($args)
f
//$args gives an array of the command-line arguments for this command
g
public function getHelp()
f
return'Usage:how to use this command';
g
g
6.3.9 Module
Please refer to the section about modules on how to create a module.
A general guideline for developing a module is that it should be self-contained.Resource
les (such as CSS,JavaScript,images) that are used by a module should be distributed
together with the module.And the module should publish them so that they can be
Web-accessible.
6.4 Using 3rd-Party Libraries 123
6.3.10 Generic Component
Developing a generic component extension is like writing a class.Again,the component
should also be self-contained so that it can be easily used by other developers.
6.4 Using 3rd-Party Libraries
Yii is carefully designed so that third-party libraries can be easily integrated to further
extend Yii's functionalities.When using third-party libraries in a project,developers often
encounter issues about class naming and le inclusion.Because all Yii classes are prexed
with letter C,it is less likely class naming issue would occur;and because Yii relies on SPL
autoload to perform class le inclusion,it can play nicely with other libraries if they use
the same autoloading feature or PHP include path to include class les.
Below we use an example to illustrate how to use the Zend
Search
Lucene component from
the Zend framework in a Yii application.
First,we extract the Zend framework release le to a directory under protected/vendors,
assuming protected is the application base directory.Verify that the le protected/
vendors/Zend/Search/Lucene.php exists.
Second,at the beginning of a controller class le,insert the following lines:
Yii::import('application.vendors.*');
require
once('Zend/Search/Lucene.php');
The above code includes the class le Lucene.php.Because we are using a relative path,
we need to change the PHP include path so that the le can be located correctly.This is
done by calling Yii::import before require
once.
Once the above set up is ready,we can use the Lucene class in a controller action,like the
following:
$lucene=new Zend
Search
Lucene($pathOfIndex);
$hits=$lucene->find(strtolower($keyword));
124 6.Extending Yii
Chapter 7
Testing
7.1 Overview
Note:The testing support described in this chapter requires Yii version 1.1 or
higher.This does not mean,however,that you cannot test applications developed
using Yii 1.0.x.There are many great testing frameworks available to help you
accomplish this task,such as PHPUnit,SimpleTest.
Testing is an indispensable process of software development.Whether we are aware of
it or not,we conduct testing all the time when we are developing a Web application.
For example,when we write a class in PHP,we may use some echo or die statement to
show that we implement a method correctly;when we implement a Web page containing
a complex HTML form,we may try entering some test data to ensure the page interacts
with us as expected.More advanced developers would write some code to automate this
testing process so that each time when we need to test something,we just need to call
up the code and let the computer to perform testing for us.This is known as automated
testing,which is the main topic of this chapter.
The testing support provided by Yii includes unit testing and functional testing.
A unit test veries that a single unit of code is working as expected.In object-oriented
programming,the most basic code unit is a class.A unit test thus mainly needs to verify
that each of the class interface methods works properly.That is,given dierent input
parameters,the test veries the method returns expected results.Unit tests are usually
developed by people who write the classes being tested.
A functional test veries that a feature (e.g.post management in a blog system) is working
as expected.Compared with a unit test,a functional test sits at a higher level because a
feature being tested often involves multiple classes.Functional tests are usually developed
by people who know very well the system requirements (they could be either developers
or quality engineers).
126 7.Testing
7.2 Test-Driven Development
Below we show the development cycles in the so-called test-driven development (TDD):
1.Create a new test that covers a feature to be implemented.The test is expected to
fail at its rst execution because the feature has yet to be implemented.
2.Run all tests and make sure the new test fails.
3.Write code to make the new test pass.
4.Run all tests and make sure they all pass.
5.Refactor the code that is newly written and make sure the tests still pass.
Repeat step 1 to 5 to push forward the functionality implementation.
7.3 Test Environment Setup
The testing supported provided by Yii requires PHPUnit 3.3+ and Selenium Remote
Control 1.0+.Please refer to their documentation on howto install PHPUnit and Selenium
Remote Control.
When we use the yiic webapp console command to create a new Yii application,it will
generate the following les and directories for us to write and perform new tests:
testdrive/
protected/containing protected application files
tests/containing tests for the application
fixtures/containing database fixtures
functional/containing functional tests
unit/containing unit tests
report/containing coverage reports
bootstrap.php the script executed at the very beginning
phpunit.xml the PHPUnit configuration file
WebTestCase.php the base class for Web-based functional tests
As shown in the above,our test code will be mainly put into three directories:fixtures,
functional and unit,and the directory report will be used to store the generated code
coverage reports.
To execute tests (whether unit tests or functional tests),we can execute the following
commands in a console window:
7.4 Test Bootstrap Script 127
% cd testdrive/protected/tests
% phpunit functional/PostTest.php//executes an individual test
% phpunit --verbose functional//executes all tests under'functional'
% phpunit --coverage-html./report unit
In the above,the last command will execute all tests under the unit directory and generate
a code-coverage report under the report directory.Note that xdebug extension must be
installed and enabled in order to generate code-coverage reports.
7.4 Test Bootstrap Script
Let's take a look what may be in the bootstrap.php le.This le is so special because it
is like the entry script and is the starting point when we execute a set of tests.
$yiit='path/to/yii/framework/yiit.php';
$config=dirname(
FILE
).'/../config/test.php';
require
once($yiit);
require
once(dirname(
FILE
).'/WebTestCase.php');
Yii::createWebApplication($config);
In the above,we rst include the yiit.php le from the Yii framework,which initializes
some global constants and includes necessary test base classes.We then create a Web
application instance using the test.php conguration le.If we check test.php,we shall
nd that it inherits from the main.php conguration le and adds a fixture application
component whose class is CDbFixtureManager.We will describe xtures in detail in the
next section.
return CMap::mergeArray(
require(dirname(
FILE
).'/main.php'),
array(
'components'=>array(
'fixture'=>array(
'class'=>'system.test.CDbFixtureManager',
),
/* uncomment the following to provide test database connection
'db'=>array(
'connectionString'=>'DSN for test database',
),
*/
),
)
);
128 7.Testing
When we run tests that involve database,we should provide a test database so that
the test execution does not interfere with normal development or production activities.
To do so,we just need to uncomment the db conguration in the above and ll in the
connectionString property with the DSN (data source name) to the test database.
With such a bootstrap script,when we run unit tests,we will have an application instance
that is nearly the same as the one that serves for Web requests.The main dierence is
that it has the xture manager and is using the test database.
7.5 Dening Fixtures
Automated tests need to be executed many times.To ensure the testing process is repeat-
able,we would like to run the tests in some known state called xture.For example,to
test the post creation feature in a blog application,each time when we run the tests,the
tables storing relevant data about posts (e.g.the Post table,the Comment table) should
be restored to some xed state.The PHPUnit documentation has described well about
generic xture setup.In this section,we mainly describe how to set up database xtures,
as we just described in the example.
Setting up database xtures is perhaps one of the most time-consuming parts in testing
database-backed Web applications.Yii introduces the CDbFixtureManager application
component to alleviate this problem.It basically does the following things when running
a set of tests:
Before all tests run,it resets all tables relevant to the tests to some known state.
Before a single test method runs,it resets the specied tables to some known state.
During the execution of a test method,it provides access to the rows of the data
that contribute to the xture.
To use CDbFixtureManager,we congure it in the application conguration as follows,
return array(
'components'=>array(
'fixture'=>array(
'class'=>'system.test.CDbFixtureManager',
),
),
);
We then provide the xture data under the directory protected/tests/fixtures.This
7.5 Dening Fixtures 129
directory may be customized to be a dierent one by conguring the CDbFixtureMan-
ager::basePath property in the application conguration.The xture data is organized as
a collection of PHP les called xture les.Each xture le returns an array representing
the initial rows of data for a particular table.The le name is the same as the table name.
The following is an example of the xture data for the Post table stored in a le named
Post.php:
<?php
return array(
'sample1'=>array(
'title'=>'test post 1',
'content'=>'test post content 1',
'createTime'=>1230952187,
'authorId'=>1,
),
'sample2'=>array(
'title'=>'test post 2',
'content'=>'test post content 2',
'createTime'=>1230952287,
'authorId'=>1,
),
);
As we can see,two rows of data are returned in the above.Each row is represented as an
associative array whose keys are column names and whose values are the corresponding
column values.In addition,each row is indexed by a string (e.g.sample1,sample2) which
is called row alias.Later when we write test scripts,we can conveniently refer to a row
by its alias.We will describe this in detail in the next section.
You may notice that we do not specify the id column values in the above xture.This is
because the id column is dened to be an auto-incremental primary key whose value will
be lled up when we insert new rows.
When CDbFixtureManager is referenced for the rst time,it will go through every x-
ture le and use it to reset the corresponding table.It resets a table by truncating the
table,resetting the sequence value for the table's auto-incremental primary key,and then
inserting the rows of data from the xture le into the table.
Sometimes,we may not want to reset every table which has a xture le before we run
a set of tests,because resetting too many xture les could take very long time.In this
case,we can write a PHP script to do the initialization work in a customized way.The
script should be saved in a le named init.php under the same directory that contains
other xture les.When CDbFixtureManager detects the existence of this script,it will
execute this script instead of resetting every table.
130 7.Testing
It is also possible that we do not like the default way of resetting a table,i.e.,truncating
it and inserting it with the xture data.If this is the case,we can write an initialization
script for the specic xture le.The script must be named as the table name suxed
with.init.php.For example,the initialization script for the Post table would be Post.
init.php.When CDbFixtureManager sees this script,it will execute this script instead of
using the default way to reset the table.
Tip:Having too many xture les could increase the test time dramatically.For
this reason,you should only provide xture les for those tables whose content may
change during the test.Tables that serve as look-ups do not change and thus do
not need xture les.
In the next two sections,we will describe how to make use of the xtures managed by
CDbFixtureManager in unit tests and functional tests.
7.6 Unit Testing
Because the Yii testing framework is built on top of PHPUnit,it is recommended that
you go through the PHPUnit documentation rst to get the basic understanding on how
to write a unit test.We summarize in the following the basic principles of writing a unit
test in Yii:
A unit test is written in terms of a class XyzTest which extends from CTestCase or
CDbTestCase,where Xyz stands for the class being tested.For example,to test the
Post class,we would name the corresponding unit test as PostTest by convention.
The base class CTestCase is meant for generic unit tests,while CDbTestCase is
suitable for testing active record model classes.Because PHPUnit
Framework
TestCase
is the ancestor class for both classes,we can use all methods inherited fromthis class.
The unit test class is saved in a PHP le named as XyzTest.php.By convention,the
unit test le may be stored under the directory protected/tests/unit.
The test class mainly contains a set of test methods named as testAbc,where Abc is
often the name of the class method to be tested.
A test method usually contains a sequence of assertion statements (e.g.assertTrue,
assertEquals) which serve as checkpoints on validating the behavior of the target
class.
In the following,we mainly describe how to write unit tests for active record model classes.
We will extend our test classes fromCDbTestCase because it provides the database xture
7.6 Unit Testing 131
support that we introduced in the previous section.
Assume we want to test the Comment model class in the blog demo.We start by creating
a class named CommentTest and saving it as protected/tests/unit/CommentTest.php:
class CommentTest extends CDbTestCase
f
public $fixtures=array(
'posts'=>'Post',
'comments'=>'Comment',
);
......
g
In this class,we specify the fixtures member variable to be an array that species which
xtures will be used by this test.The array represents a mapping from xture names to
model class names or xture table names (e.g.from xture name posts to model class
Post).Note that when mapping to xture table names,we should prex the table name
with a colon (e.g.:Post) to dierentiate it from model class name.And when using model
class names,the corresponding tables will be considered as xture tables.As we described
earlier,xture tables will be reset to some known state each time when a test method is
executed.
Fixture names allow us to access the xture data in test methods in a convenient way.
The following code shows its typical usage:
//return all rows in the'Comment'fixture table
$comments = $this->comments;
//return the row whose alias is'sample1'in the`Post`fixture table
$post = $this->posts['sample1'];
//return the AR instance representing the'sample1'fixture data row
$post = $this->posts('sample1');
Note:If a xture is declared using its table name (e.g.'posts'=>':Post'),then
the third usage in the above is not valid because we have no information about
which model class the table is associated with.
Next,we write the testApprove method to test the approve method in the Comment model
class.The code is very straightforward:we rst insert a comment that is pending status;
we then verify this comment is in pending status by retrieving it fromdatabase;and nally
we call the approve method and verify the status is changed as expected.
132 7.Testing
public function testApprove()
f
//insert a comment in pending status
$comment=new Comment;
$comment->setAttributes(array(
'content'=>'comment 1',
'status'=>Comment::STATUS
PENDING,
'createTime'=>time(),
'author'=>'me',
'email'=>'me@example.com',
'postId'=>$this->posts['sample1']['id'],
),false);
$this->assertTrue($comment->save(false));
//verify the comment is in pending status
$comment=Comment::model()->findByPk($comment->id);
$this->assertTrue($comment instanceof Comment);
$this->assertEquals(Comment::STATUS
PENDING,$comment->status);
//call approve() and verify the comment is in approved status
$comment->approve();
$this->assertEquals(Comment::STATUS
APPROVED,$comment->status);
$comment=Comment::model()->findByPk($comment->id);
$this->assertEquals(Comment::STATUS
APPROVED,$comment->status);
g
7.7 Functional Testing
Before reading this section,it is recommended that you read the Selenium documentation
and the PHPUnit documentation rst.We summarize in the following the basic principles
of writing a functional test in Yii:
Like unit test,a functional test is written in terms of a class XyzTest which extends
from CWebTestCase,where Xyz stands for the class being tested.Because PHPUnit
Extensions
SeleniumTestCase is the ancestor class for CWebTestCase,we can use all
methods inherited from this class.
The functional test class is saved in a PHP le named as XyzTest.php.By conven-
tion,the functional test le may be stored under the directory protected/tests/
functional.
The test class mainly contains a set of test methods named as testAbc,where Abc is
often the name of a feature to be tested.For example,to test the user login feature,
we can have a test method named as testLogin.
7.7 Functional Testing 133
A test method usually contains a sequence of statements that would issue commands
to Selenium RC to interact with the Web application being tested.It also contains
assertion statements to verify that the Web application responds as expected.
Before we describe how to write a functional test,let's take a look at the WebTestCase.php
le generated by the yiic webapp command.This le denes WebTestCase that may serve
as the base class for all functional test classes.
define('TEST
BASE
URL','http://localhost/yii/demos/blog/index-test.php/');
class WebTestCase extends CWebTestCase
f
/**
* Sets up before each test method runs.
* This mainly sets the base URL for the test application.
*/
protected function setUp()
f
parent::setUp();
$this->setBrowserUrl(TEST
BASE
URL);
g
......
g
The class WebTestCase mainly sets the base URL of the pages to be tested.Later in test
methods,we can use relative URLs to specify which pages to be tested.
We should also pay attention that in the base test URL,we use index-test.php as the
entry script instead of index.php.The only dierence between index-test.php and index.
php is that the former uses test.php as the application conguration le while the latter
main.php.
We now describe how to test the feature about showing a post in the blog demo.We rst
write the test class as follows,noting that the test class extends from the base class we
just described:
class PostTest extends WebTestCase
f
public $fixtures=array(
'posts'=>'Post',
);
public function testShow()
134 7.Testing
f
$this->open('post/1');
//verify the sample post title exists
$this->assertTextPresent($this->posts['sample1']['title']);
//verify comment form exists
$this->assertTextPresent('Leave a Comment');
g
......
g
Like writing a unit test class,we declare the xtures to be used by this test.Here we
indicate that the Post xture should be used.In the testShow test method,we rst instruct
Selenium RC to open the URL post/1.Note that this is a relative URL,and the complete
URL is formed by appending it to the base URL we set in the base class (i.e.http://
localhost/yii/demos/blog/index-test.php/post/1).We then verify that we can nd the
title of the sample1 post can be found in the current Web page.And we also verify that
the page contains the text Leave a Comment.
Tip:Before running functional tests,the Selenium-RC server must be started.This
can be done by executing the command java -jar selenium-server.jar under
your Selenium server installation directory.
Chapter 8
Special Topics
8.1 Automatic Code Generation
Starting from version 1.1.2,Yii is equipped with a Web-based code generation tool called
Gii.It supercedes the previous yiic shell generation tool which runs on command line.
In this section,we will describe how to use Gii and how to extend Gii to increase our
development productivity.
8.1.1 Using Gii
Gii is implemented in terms of a module and must be used within an existing Yii applica-
tion.To use Gii,we rst modify the application conguration as follows:
return array(
......
'modules'=>array(
'gii'=>array(
'class'=>'system.gii.GiiModule',
'password'=>'pick up a password here',
//'ipFilters'=>array(...a list of IPs...),
//'newFileMode'=>0666,
//'newDirMode'=>0777,
),
),
);
In the above,we declare a module named gii whose class is GiiModule.We also specify
a password for the module which we will be prompted for when accessing Gii.
By default for security reasons,Gii is congured to be accessible only on localhost.If we
want to make it accessible on other trustable computers,we can congure the GiiMod-
ule::ipFilters property as shown in the above code.
136 8.Special Topics
Because Gii may generate and save new code les in the existing application,we need to
make sure that the Web server process has the proper permission to do so.The above
GiiModule::newFileMode and GiiModule::newDirMode properties control how the new
les and directories should be generated.
Note:Gii is mainly provided as a development tool.Therefore,it should only be
installed on a development machine.Because it can generate new PHP script les
in the application,we should pay sucient attention to its security measures (e.g.
password,IP lters).
We can now access Gii via the URL http://hostname/path/to/index.php?r=gii.Here
we assume http://hostname/path/to/index.php is the URL for accessing the existing Yii
application.
If the existing Yii application uses path-format URLs (see URL management),we can
access Gii via the URL http://hostnamepath/to/index.php/gii.We may need to add the
following URL rules to the front of the existing URL rules:
'components'=>array(
......
'urlManager'=>array(
'urlFormat'=>'path',
'rules'=>array(
'gii'=>'gii',
'gii/<controller:nw+>'=>'gii/<controller>',
'gii/<controller:nw+>/<action:nw+>'=>'gii/<controller>/<action>',
...existing rules...
),
),
)
Gii comes with a few default code generators.Each code generator is responsible for
generating a specic type of code.For example,the controller generator generates a
controller class together with a few action view scripts;the model generator generates an
ActiveRecord class for the specied database table.
The basic workow of using a generator is as follows:
1.Enter the generator page;
2.Fill in the elds that specify the code generation parameters.For example,to use
the module generator to create a new module,you need to specify the module ID;
8.1 Automatic Code Generation 137
3.Press the Preview button to preview the code to be generated.You will see a table
showing a list of code les to be generated.You can click on any of them to preview
the code;
4.Press the Generate button to generate the code les;
5.Review the code generation log.
8.1.2 Extending Gii
While the default code generators coming with Gii can generate very powerful code,we
often want to customize them or create new ones to t for our taste and needs.For
example,we may want the generated code to be in our own favorite coding styles,or we
may want to make the code to support multiple languages.All these can be done easily
with Gii.
Gii can be extended in two ways:customizing the code templates of the existing code
generators,and writing new code generators.
Structure of a Code Generator
A code generator is stored under a directory whose name is treated as the generator name.
The directory usually consists of the following content:
model/the model generator root folder
ModelCode.php the code model used to generate code
ModelGenerator.php the code generation controller
views/containing view scripts for the generator
index.php the default view script
templates/containing code template sets
default/the'default'code template set
model.php the code template for generating model class code
Generator Search Path
Gii looks for available generators in a set of directories specied by the GiiModule::generatorPaths
property.When customization is needed,we can congure this property in the application
conguration as follows,
return array(
'modules'=>array(
138 8.Special Topics
'gii'=>array(
'class'=>'system.gii.GiiModule',
'generatorPaths'=>array(
'application.gii',//a path alias
),
),
),
);
The above conguration instructs Gii to look for generators under the directory aliased
as application.gii,in addition to the default location system.gii.generators.
It is possible to have two generators with the same name but under dierent search paths.
In this case,the generator under the path specied earlier in GiiModule::generatorPaths
will take precedence.
Customizing Code Templates
This is the easiest and the most common way of extending Gii.We use an example
to explain how to customize code templates.Assume we want to customize the code
generated by the model generator.
We rst create a directory named protected/gii/model/templates/compact.Here model
means that we are going to override the default model generator.And templates/compact
means we will add a new code template set named compact.
We then modify our application conguration to add application.gii to GiiModule::generatorPaths,
as shown in the previous sub-section.
Now open the model code generator page.Click on the Code Template eld.We should see
a dropdown list which contains our newly created template directory compact.However,
if we choose this template to generate the code,we will see an error.This is because we
have yet to put any actual code template le in this new compact template set.
Copy the le framework/gii/generators/model/templates/default/model.php to protected/
gii/model/templates/compact.If we try generating again with the compact template,we
should succeed.However,the code generated is no dierent from the one generated by
the default template set.
It is time for us to do the real customization work.Open the le protected/gii/model/
templates/compact/model.php to edit it.Remember that this le will be used like a view
script,which means it can contain PHP expressions and statements.Let's modify the
8.1 Automatic Code Generation 139
template so that the attributeLabels() method in the generated code uses Yii::t() to
translate the attribute labels:
public function attributeLabels()
f
return array(
<?php foreach($labels as $name=>$label):?>
<?php echo"'$name'=> Yii::t('application','$label'),nn";?>
<?php endforeach;?>
);
g
In each code template,we can access some predened variables,such as $labels in the
above example.These variables are provided by the corresponding code generator.Dier-
ent code generators may provide dierent set of variables in their code templates.Please
read the description in the default code templates carefully.
Creating New Generators
In this sub-section,we show how to create a new generator that can generate a new widget
class.
We rst create a directory named protected/gii/widget.Under this directory,we will
create the following les:
WidgetGenerator.php:contains the WidgetGenerator controller class.This is the
entry point of the widget generator.
WidgetCode.php:contains the WidgetCode model class.This class has the main logic
for code generation.
views/index.php:the view script showing the code generator input form.
templates/default/widget.php:the default code template for generating a widget
class le.
<h4 id="creating-x-3029x">Creating WidgetGenerator.php</h4>
The WidgetGenerator.php le is extremely simple.It only contains the following code:
class WidgetGenerator extends CCodeGenerator
140 8.Special Topics
f
public $codeModel='application.gii.widget.WidgetCode';
g
In the above code,we specify that the generator will use the model class whose path alias
is application.gii.widget.WidgetCode.The WidgetGenerator class extends from CCode-
Generator which implements a lot of functionalities,including the controller actions needed
to coordinate the code generation process.
<h4 id="creating-x-3032x">Creating WidgetCode.php</h4>
The WidgetCode.php le contains the WidgetCode model class that has the main logic for
generating a widget class based on the user input.In this example,we assume that the
only input we want from the user is the widget class name.Our WidgetCode looks like the
following:
class WidgetCode extends CCodeModel
f
public $className;
public function rules()
f
return array
merge(parent::rules(),array(
array('className','required'),
array('className','match','pattern'=>'/^nw+$/'),
));
g
public function attributeLabels()
f
return array
merge(parent::attributeLabels(),array(
'className'=>'Widget Class Name',
));
g
public function prepare()
f
$path=Yii::getPathOfAlias('application.components.'.$this->className).'.php';
$code=$this->render($this->templatepath.'/widget.php');
$this->files[]=new CCodeFile($path,$code);
g
g
The WidgetCode class extends from CCodeModel.Like a normal model class,in this class
we can declare rules() and attributeLabels() to validate user inputs and provide at-
8.1 Automatic Code Generation 141
tribute labels,respectively.Note that because the base class CCodeModel already denes
some rules and attribute labels,we should merge them with our new rules and labels here.
The prepare() method prepares the code to be generated.Its main task is to prepare
a list of CCodeFile objects,each of which represent a code le being generated.In our
example,we only need to create one CCodeFile object that represents the widget class le
being generated.The new widget class will be generated under the protected/components
directory.We call CCodeFile::render method to generate the actual code.This method
includes the code template as a PHP script and returns the echoed content as the generated
code.
<h4 id="creating-x-3035x">Creating views/index.php</h4>
Having the controller (WidgetGenerator) and the model (WidgetCode),it is time for us to
create the view views/index.php.
<h1>Widget Generator</h1>
<?php $form=$this->beginWidget('CCodeForm',array('model'=>$model));?>
<div class="row">
<?php echo $form->labelEx($model,'className');?>
<?php echo $form->textField($model,'className',array('size'=>65));?>
<div class="tooltip">
Widget class name must only contain word characters.
</div>
<?php echo $form->error($model,'className');?>
</div>
<?php $this->endWidget();?>
In the above,we mainly display a form using the CCodeForm widget.In this form,we
display the eld to collect the input for the className attribute in WidgetCode.
When creating the form,we can exploit two nice features provided by the CCodeForm
widget.One is about input tooltips.The other is about sticky inputs.
If you have tried any default code generator,you will notice that when setting focus in
one input eld,a nice tooltip will show up next to the eld.This can easily achieved here
by writing next to the input eld a div whose CSS class is tooltip.
For some input elds,we may want to remember their last valid values so that the user
can save the trouble of re-entering themeach time they use the generator to generate code.
An example is the input eld collecting the controller base class name default controller
142 8.Special Topics
generator.These sticky elds are initially displayed as highlighted static text.If we click
on them,they will turn into input elds to take user inputs.
In order to declare an input eld to be sticky,we need to do two things.
First,we need to declare a sticky validation rule for the corresponding model attribute.
For example,the default controller generator has the following rule to declare that baseClass
and actions attributes are sticky:
public function rules()
f
return array
merge(parent::rules(),array(
......
array('baseClass,actions','sticky'),
));
g
Second,we need to add a CSS class named sticky to the container div of the input eld
in the view,like the following:
<div class="row sticky">
...input field here...
</div>
<h4 id="creating-x-3038x">Creating templates/default/widget.php</h4>
Finally,we create the code template templates/default/widget.php.As we described
earlier,this is used like a view script that can contain PHP expressions and statements.
In a code template,we can always access the $this variable which refers to the code
model object.In our example,$this refers to the WidgetModel object.We can thus get
the user-entered widget class name via $this->className.
<?php echo'<?php';?>
class <?php echo $this->className;?> extends CWidget
f
public function run()
f
g
g
This concludes the creation of a new code generator.We can access this code generator
immediately via the URL http://hostname/path/to/index.php?r=gii/widget.
8.2 URL Management 143
8.2 URL Management
Complete URL management for a Web application involves two aspects.First,when a user
request comes in terms of a URL,the application needs to parse it into understandable
parameters.Second,the application needs to provide a way of creating URLs so that
the created URLs can be understood by the application.For a Yii application,these are
accomplished with the help of CUrlManager.
8.2.1 Creating URLs
Although URLs can be hardcoded in controller views,it is often moreexible to create
them dynamically:
$url=$this->createUrl($route,$params);
where $this refers to the controller instance;$route species the route of the request;and
$params is a list of GET parameters to be appended to the URL.
By default,URLs created by createUrl is in the so-called get format.For example,given
$route='post/read'and $params=array('id'=>100),we would obtain the following URL:
/index.php?r=post/read&id=100
where parameters appear in the query string as a list of Name=Value concatenated with the
ampersand characters,and the r parameter species the request route.This URL format
is not very user-friendly because it requires several non-word characters.
We could make the above URL look cleaner and more self-explanatory by using the so-
called path format which eliminates the query string and puts the GET parameters into
the path info part of URL:
/index.php/post/read/id/100
To change the URL format,we should congure the urlManager application component
so that createUrl can automatically switch to the new format and the application can
properly understand the new URLs:
array(
......
'components'=>array(
144 8.Special Topics
......
'urlManager'=>array(
'urlFormat'=>'path',
),
),
);
Note that we do not need to specify the class of the urlManager component because it is
pre-declared as CUrlManager in CWebApplication.
Tip:The URL generated by the createUrl method is a relative one.In order to get
an absolute URL,we can prex it with Yii::app()->request->hostInfo,or call
createAbsoluteUrl.
8.2.2 User-friendly URLs
When path is used as the URL format,we can specify some URL rules to make our URLs
even more user-friendly.For example,we can generate a URL as short as/post/100,
instead of the lengthy/index.php/post/read/id/100.URL rules are used by CUrlManager
for both URL creation and parsing purposes.
To specify URL rules,we need to congure the rules property of the urlManager application
component:
array(
......
'components'=>array(
......
'urlManager'=>array(
'urlFormat'=>'path',
'rules'=>array(
'pattern1'=>'route1',
'pattern2'=>'route2',
'pattern3'=>'route3',
),
),
),
);
The rules are specied as an array of pattern-route pairs,each corresponding to a single
rule.The pattern of a rule is a string used to match the path info part of URLs.And the
route of a rule should refer to a valid controller route.
8.2 URL Management 145
Besides the above pattern-route format,a rule may also be specied with customized
options,like the following:
'pattern1'=>array('route1','urlSuffix'=>'.xml','caseSensitive'=>false)
In the above,the array contains a list of customized options.As of version 1.1.0,the
following options are available:
urlSux:the URL sux used specically for this rule.Defaults to null,meaning
using the value of CUrlManager::urlSux.
caseSensitive:whether this rule is case sensitive.Defaults to null,meaning using
the value of CUrlManager::caseSensitive.
defaultParams:the default GET parameters (name=>value) that this rule provides.When
this rule is used to parse the incoming request,the values declared in this property will be
injected into
G
ET:matchV alue:whethertheGETparametervaluesshouldmatchthecorrespondingsub
patternsintherulewhencreatingaURL:Defaultstonull;meaningusingthevalueofCUrlManager::
matchV alue:Ifthispropertyisfalse;itmeansarulewillbeusedforcreatingaURLifitsrouteandparameternamesmatchthegivenones:Ifthispropertyissettrue;thenthegivenparametervaluesmustalsomatchthecorrespondingparametersub
patterns:Notethatsettingthispropertytotruewilldegradeperformance:
Using Named Parameters
A rule can be associated with a few GET parameters.These GET parameters appear in
the rule's pattern as special tokens in the following format:
<ParamName:ParamPattern>
where ParamName species the name of a GET parameter,and the optional ParamPattern
species the regular expression that should be used to match the value of the GET pa-
rameter.In case when ParamPattern is omitted,it means the parameter should match any
characters except the slash/.When creating a URL,these parameter tokens will be re-
placed with the corresponding parameter values;when parsing a URL,the corresponding
GET parameters will be populated with the parsed results.
Let's use some examples to explain how URL rules work.We assume that our rule set
consists of three rules:
array(
146 8.Special Topics
'posts'=>'post/list',
'post/<id:nd+>'=>'post/read',
'post/<year:ndf4g>/<title>'=>'post/read',
)
Calling $this->createUrl('post/list') generates/index.php/posts.The rst rule
is applied.
Calling $this->createUrl('post/read',array('id'=>100)) generates/index.php/post/
100.The second rule is applied.
Calling $this->createUrl('post/read',array('year'=>2008,'title'=>'a sample post'))
generates/index.php/post/2008/a%20sample%20post.The third rule is applied.
Calling $this->createUrl('post/read') generates/index.php/post/read.None of
the rules is applied.
In summary,when using createUrl to generate a URL,the route and the GET parameters
passed to the method are used to decide which URL rule to be applied.If every parameter
associated with a rule can be found in the GET parameters passed to createUrl,and if
the route of the rule also matches the route parameter,the rule will be used to generate
the URL.
If the GETparameters passed to createUrl are more than those required by a rule,the addi-
tional parameters will appear in the query string.For example,if we call $this->createUrl('post/
read',array('id'=>100,'year'=>2008)),we would obtain/index.php/post/100?year=2008.
In order to make these additional parameters appear in the path info part,we should ap-
pend/* to the rule.Therefore,with the rule post/<id:nd+>/*,we can obtain the URL as
/index.php/post/100/year/2008.
As we mentioned,the other purpose of URL rules is to parse the requesting URLs.Nat-
urally,this is an inverse process of URL creation.For example,when a user requests for
/index.php/post/100,the second rule in the above example will apply,which resolves in
the route post/read and the GET parameter array('id'=>100) (accessible via $
GET).
Note:Using URL rules will degrade application performance.This is because when
parsing the request URL,CUrlManager will attempt to match it with each rule until
one can be applied.The more the number of rules,the more the performance impact.
Therefore,a high-trac Web application should minimize its use of URL rules.
8.2 URL Management 147
Parameterizing Routes
Starting from version 1.0.5,we may reference named parameters in the route part of a
rule.This allows a rule to be applied to multiple routes based on matching criteria.It
may also help reduce the number of rules needed for an application,and thus improve the
overall performance.
We use the following example rules to illustrate how to parameterize routes with named
parameters:
array(
'<
c:(post|comment)>/<id:nd+>/<
a:(create|update|delete)>'=>'<
c>/<
a>',
'<
c:(post|comment)>/<id:nd+>'=>'<
c>/read',
'<
c:(post|comment)>s'=>'<
c>/list',
)
In the above,we use two named parameters in the route part of the rules:
c and
a.The
former matches a controller ID to be either post or comment,while the latter matches an
action ID to be create,update or delete.You may name the parameters dierently as
long as they do not conict with GET parameters that may appear in URLs.
Using the aboving rules,the URL/index.php/post/123/create would be parsed as the
route post/create with GET parameter id=123.And given the route comment/list and
GET parameter page=2,we can create a URL/index.php/comments?page=2.
Parameterizing Hostnames
Starting fromversion 1.0.11,it is also possible to include hostname into the rules for parsing
and creating URLs.One may extract part of the hostname to be a GET parameter.
For example,the URL http://admin.example.com/en/profile may be parsed into GET
parameters user=admin and lang=en.On the other hand,rules with hostname may also
be used to create URLs with paratermized hostnames.
In order to use parameterized hostnames,simply declare URL rules with host info,e.g.:
array(
'http://<user:nw+>.example.com/<lang:nw+>/profile'=>'user/profile',
)
The above example says that the rst segment in the hostname should be treated as user
parameter while the rst segment in the path info should be lang parameter.The rule
corresponds to the user/profile route.
148 8.Special Topics
Note that CUrlManager::showScriptName will not take eect when a URL is being created
using a rule with parameterized hostname.
Also note that the rule with parameterized hostname should NOT contain the sub-folder
if the application is under a sub-folder of the Web root.For example,if the application is
under http://www.example.com/sandbox/blog,then we should still use the same URL rule
as described above without the sub-folder sandbox/blog.
Hiding index.php
There is one more thing that we can do to further clean our URLs,i.e.,hiding the entry
script index.php in the URL.This requires us to congure the Web server as well as the
urlManager application component.
We rst need to congure the Web server so that a URL without the entry script can still
be handled by the entry script.For Apache HTTP server,this can be done by turning
on the URL rewriting engine and specifying some rewriting rules.We can create the le
/wwwroot/blog/.htaccess with the following content.Note that the same content can also
be put in the Apache conguration le within the Directory element for/wwwroot/blog.
Options +FollowSymLinks
IndexIgnore */*
RewriteEngine on
#if a directory or a file exists,use it directly
RewriteCond %{REQUEST_FILENAME}!-f
RewriteCond %{REQUEST_FILENAME}!-d
#otherwise forward it to index.php
RewriteRule.index.php
We then congure the showScriptName property of the urlManager component to be
false.
Now if we call $this->createUrl('post/read',array('id'=>100)),we would obtain the
URL/post/100.More importantly,this URL can be properly recognized by our Web
application.
8.3 Authentication and Authorization 149
Faking URL Sux
We may also add some sux to our URLs.For example,we can have/post/100.html
instead of/post/100.This makes it look more like a URL to a static Web page.To do so,
simply congure the urlManager component by setting its urlSux property to the sux
you like.
8.3 Authentication and Authorization
Authentication and authorization are required for a Web page that should be limited to
certain users.Authentication is about verifying whether someone is who he claims he
is.It usually involves a username and a password,but may include any other methods of
demonstrating identity,such as a smart card,ngerprints,etc.Authorization is nding out
if the person,once identied (authenticated),is permitted to manipulate specic resources.
This is usually determined by nding out if that person is of a particular role that has
access to the resources.
Yii has a built-in authentication/authorization (auth) framework which is easy to use and
can be customized for special needs.
The central piece in the Yii auth framework is a pre-declared user application component
which is an object implementing the IWebUser interface.The user component represents
the persistent identity information for the current user.We can access it at any place
using Yii::app()->user.
Using the user component,we can check if a user is logged in or not via CWebUser::isGuest;
we can login and logout a user;we can check if the user can perform specic operations
by calling CWebUser::checkAccess;and we can also obtain the unique identier and other
persistent identity information about the user.
8.3.1 Dening Identity Class
In order to authenticate a user,we dene an identity class which contains the actual au-
thentication logic.The identity class should implement the IUserIdentity interface.Dif-
ferent classes may be implemented for dierent authentication approaches (e.g.OpenID,
LDAP).A good start is by extending CUserIdentity which is a base class for the authen-
tication approach based on username and password.
The main work in dening an identity class is the implementation of the IUserIden-
tity::authenticate method.An identity class may also declare additional identity infor-
mation that needs to be persistent during the user session.
150 8.Special Topics
In the following example,we validate the given username and password against the user
table in a database using Active Record.We also override the getId method to return the
id variable which is set during authentication (the default implementation would return
the username as the ID).During authentication,we store the retrieved title information
in a state with the same name by calling CBaseUserIdentity::setState.
class UserIdentity extends CUserIdentity
f
private $
id;
public function authenticate()
f
$record=User::model()->findByAttributes(array('username'=>$this->username));
if($record===null)
$this->errorCode=self::ERROR
USERNAME
INVALID;
else if($record->password!==md5($this->password))
$this->errorCode=self::ERROR
PASSWORD
INVALID;
else
f
$this->
id=$record->id;
$this->setState('title',$record->title);
$this->errorCode=self::ERROR
NONE;
g
return!$this->errorCode;
g
public function getId()
f
return $this->
id;
g
g
Information stored in a state (by calling CBaseUserIdentity::setState) will be passed to
CWebUser which stores them in a persistent storage,such as session.These information
can be accessed like properties of CWebUser.For example,we can obtain the title
information of the current user by Yii::app()->user->title (This has been available since
version 1.0.3.In prior versions,we should use Yii::app()->user->getState('title'),
instead.)
Info:By default,CWebUser uses session as persistent storage for user identity
information.If cookie-based login is enabled (by setting CWebUser::allowAutoLogin
to be true),the user identity information may also be saved in cookie.Make sure
you do not declare sensitive information (e.g.password) to be persistent.
8.3 Authentication and Authorization 151
8.3.2 Login and Logout
Using the identity class and the user component,we can implement login and logout
actions easily.
//Login a user with the provided username and password.
$identity=new UserIdentity($username,$password);
if($identity->authenticate())
Yii::app()->user->login($identity);
else
echo $identity->errorMessage;
......
//Logout the current user
Yii::app()->user->logout();
By default,a user will be logged out after a certain period of inactivity,depending on the
session conguration.To change this behavior,we can set the allowAutoLogin property
of the user component to be true and pass a duration parameter to the CWebUser::login
method.The user will then remain logged in for the specied duration,even if he closes
his browser window.Note that this feature requires the user's browser to accept cookies.
//Keep the user logged in for 7 days.
//Make sure allowAutoLogin is set true for the user component.
Yii::app()->user->login($identity,3600*24*7);
8.3.3 Access Control Filter
Access control lter is a preliminary authorization scheme that checks if the current user
can perform the requested controller action.The authorization is based on user's name,
client IP address and request types.It is provided as a lter named as"accessControl".
Tip:Access control lter is sucient for simple scenarios.For complex access
control,you may use role-based access (RBAC) which is to be covered shortly.
To control the access to actions in a controller,we install the access control lter by
overriding CController::lters (see Filter for more details about installing lters).
class PostController extends CController
f
......
public function filters()
152 8.Special Topics
f
return array(
'accessControl',
);
g
g
In the above,we specify that the access control lter should be applied to every action
of PostController.The detailed authorization rules used by the lter are specied by
overriding CController::accessRules in the controller class.
class PostController extends CController
f
......
public function accessRules()
f
return array(
array('deny',
'actions'=>array('create','edit'),
'users'=>array('?'),
),
array('allow',
'actions'=>array('delete'),
'roles'=>array('admin'),
),
array('deny',
'actions'=>array('delete'),
'users'=>array('*'),
),
);
g
g
The above code species three rules,each represented as an array.The rst element of
the array is either'allow'or'deny'and the rest name-value pairs specify the pattern
parameters of the rule.These rules read:the create and edit actions cannot be executed
by anonymous users;the delete action can be executed by users with admin role;and the
delete action cannot be executed by anyone.
The access rules are evaluated one by one in the order they are specied.The rst rule
that matches the current pattern (e.g.username,roles,client IP,address) determines the
authorization result.If this rule is an allow rule,the action can be executed;if it is a deny
rule,the action cannot be executed;if none of the rules matches the context,the action
can still be executed.
8.3 Authentication and Authorization 153
Tip:To ensure an action does not get executed under certain contexts,it is ben-
ecial to always specify a matching-all deny rule at the end of rule set,like the
following:
return array(
//...other rules...
//the following rule denies'delete'action for all contexts
array('deny',
'actions'=>array('delete'),
),
);
The reason for this rule is because if none of the rules matches a context,an action
will be executed.
An access rule can match the following context parameters:
actions:species which actions this rule matches.This should be an array of action
IDs.The comparison is case-insensitive.
controllers:species which controllers this rule matches.This should be an array of
controller IDs.The comparison is case-insensitive.This option has been available
since version 1.0.4.
users:species which users this rule matches.The current user's name is used for
matching.The comparison is case-insensitive.Three special characters can be used
here:
{ *:any user,including both anonymous and authenticated users.
{?:anonymous users.
{ @:authenticated users.
roles:species which roles that this rule matches.This makes use of the feature
to be described in the next subsection.In particular,the rule is applied if CWe-
bUser::checkAccess returns true for one of the roles.Note,you should mainly use
roles in an allow rule because by denition,a role represents a permission to do
something.Also note,although we use the term roles here,its value can actually
be any auth item,including roles,tasks and operations.
ips:species which client IP addresses this rule matches.
verbs:species which request types (e.g.GET,POST) this rule matches.The compar-
ison is case-insensitive.
154 8.Special Topics
expression:species a PHP expression whose value indicates whether this rule
matches.In the expression,you can use variable $user which refers to Yii::app()->user.
This option has been available since version 1.0.3.
Handling Authorization Result
When authorization fails,i.e.,the user is not allowed to perform the specied action,one
of the following two scenarios may happen:
If the user is not logged in and if the loginUrl property of the user component is
congured to be the URL of the login page,the browser will be redirected to that
page.Note that by default,loginUrl points to the site/login page.
Otherwise an HTTP exception will be displayed with error code 403.
When conguring the loginUrl property,one can provide a relative or absolute URL.One
can also provide an array which will be used to generate a URL by calling CWebAppli-
cation::createUrl.The rst array element should specify the route to the login controller
action,and the rest name-value pairs are GET parameters.For example,
array(
......
'components'=>array(
'user'=>array(
//this is actually the default value
'loginUrl'=>array('site/login'),
),
),
)
If the browser is redirected to the login page and the login is successful,we may want to
redirect the browser back to the page that caused the authorization failure.How do we
know the URL for that page?We can get this information from the returnUrl property
of the user component.We can thus do the following to perform the redirection:
Yii::app()->request->redirect(Yii::app()->user->returnUrl);
8.3.4 Role-Based Access Control
Role-Based Access Control (RBAC) provides a simple yet powerful centralized access
control.Please refer to the Wiki article for more details about comparing RBAC with
other more traditional access control schemes.
8.3 Authentication and Authorization 155
Yii implements a hierarchical RBAC scheme via its authManager application component.
In the following,we rst introduce the main concepts used in this scheme;we then describe
how to dene authorization data;at the end we show how to make use of the authorization
data to perform access checking.
Overview
A fundamental concept in Yii's RBAC is authorization item.An authorization item is a
permission to do something (e.g.creating new blog posts,managing users).According to
its granularity and targeted audience,authorization items can be classied as operations,
tasks and roles.A role consists of tasks,a task consists of operations,and an operation is
a permission that is atomic.For example,we can have a system with administrator role
which consists of post management task and user management task.The user management
task may consist of create user,update user and delete user operations.For more
exibility,Yii also allows a role to consist of other roles or operations,a task to consist of
other tasks,and an operation to consist of other operations.
An authorization item is uniquely identied by its name.
An authorization itemmay be associated with a business rule.A business rule is a piece of
PHP code that will be executed when performing access checking with respect to the item.
Only when the execution returns true,will the user be considered to have the permission
represented by the item.For example,when dening an operation updatePost,we would
like to add a business rule that checks if the user ID is the same as the post's author ID
so that only the author himself can have the permission to update a post.
Using authorization items,we can build up an authorization hierarchy.An itemA is a par-
ent of another item B in the hierarchy if A consists of B (or say A inherits the permission(s)
represented by B).An item can have multiple child items,and it can also have multipe
parent items.Therefore,an authorization hierarchy is a partial-order graph rather than a
tree.In this hierarchy,role items sit on top levels,operation items on bottom levels,while
task items in between.
Once we have an authorization hierarchy,we can assign roles in this hierarchy to appli-
cation users.A user,once assigned with a role,will have the permissions represented by
the role.For example,if we assign the administrator role to a user,he will have the
administrator permissions which include post management and user management (and the
corresponding operations such as create user).
Now the fun part starts.In a controller action,we want to check if the current user can
delete the specied post.Using the RBAC hierarchy and assignment,this can be done
156 8.Special Topics
easily as follows:
if(Yii::app()->user->checkAccess('deletePost'))
f
//delete the post
g
Conguring Authorization Manager
Before we set o to dene an authorization hierarchy and perform access checking,we
need to congure the authManager application component.Yii provides two types of
authorization managers:CPhpAuthManager and CDbAuthManager.The former uses a
PHP script le to store authorization data,while the latter stores authorization data in
database.When we congure the authManager application component,we need to specify
which component class to use and what are the initial property values for the component.
For example,
return array(
'components'=>array(
'db'=>array(
'class'=>'CDbConnection',
'connectionString'=>'sqlite:path/to/file.db',
),
'authManager'=>array(
'class'=>'CDbAuthManager',
'connectionID'=>'db',
),
),
);
We can then access the authManager application component using Yii::app()->authManager.
Dening Authorization Hierarchy
Dening authorization hierarchy involves three steps:dening authorization items,estab-
lishing relationships between authorization items,and assigning roles to application users.
The authManager application component provides a whole set of APIs to accomplish these
tasks.
To dene an authorization item,call one of the following methods,depending on the type
of the item:
8.3 Authentication and Authorization 157
CAuthManager::createRole
CAuthManager::createTask
CAuthManager::createOperation
Once we have a set of authorization items,we can call the following methods to establish
relationships between authorization items:
CAuthManager::addItemChild
CAuthManager::removeItemChild
CAuthItem::addChild
CAuthItem::removeChild
And nally,we call the following methods to assign role items to individual users:
CAuthManager::assign
CAuthManager::revoke
Below we show an example about building an authorization hierarchy with the provided
APIs:
$auth=Yii::app()->authManager;
$auth->createOperation('createPost','create a post');
$auth->createOperation('readPost','read a post');
$auth->createOperation('updatePost','update a post');
$auth->createOperation('deletePost','delete a post');
$bizRule='return Yii::app()->user->id==$params["post"]->authID;';
$task=$auth->createTask('updateOwnPost','update a post by author himself',$bizRule);
$task->addChild('updatePost');
$role=$auth->createRole('reader');
$role->addChild('readPost');
$role=$auth->createRole('author');
$role->addChild('reader');
$role->addChild('createPost');
$role->addChild('updateOwnPost');
158 8.Special Topics
$role=$auth->createRole('editor');
$role->addChild('reader');
$role->addChild('updatePost');
$role=$auth->createRole('admin');
$role->addChild('editor');
$role->addChild('author');
$role->addChild('deletePost');
$auth->assign('reader','readerA');
$auth->assign('author','authorB');
$auth->assign('editor','editorC');
$auth->assign('admin','adminD');
Info:While the above example looks long and tedious,it is mainly for demonstrative
purpose.Developers usually need to develop some user interfaces so that end users
can use to establish an authorization hierarchy more intuitively.
Using Business Rules
When we are dening the authorization hierarchy,we can associate a role,a task or an
operation with a so-called business rule.We may also associate a business rule when we
assign a role to a user.A business rule is a piece of PHP code that is executed when we
perform access checking.The returning value of the code is used to determine if the role
or assignment applies to the current user.In the example above,we associated a business
rule with the updateOwnPost task.In the business rule we simply check if the current user
ID is the same as the specied post's author ID.The post information in the $params array
is supplied by developers when performing access checking.
Access Checking
To perform access checking,we rst need to know the name of the authorization item.
For example,to check if the current user can create a post,we would check if he has the
permission represented by the createPost operation.We then call CWebUser::checkAccess
to perform the access checking:
if(Yii::app()->user->checkAccess('createPost'))
f
//create post
g
8.3 Authentication and Authorization 159
If the authorization rule is associated with a business rule which requires additional pa-
rameters,we can pass them as well.For example,to check if a user can update a post,we
would do
$params=array('post'=>$post);
if(Yii::app()->user->checkAccess('updateOwnPost',$params))
f
//update post
g
Using Default Roles
Note:The default role feature has been available since version 1.0.3
Many Web applications need some very special roles that would be assigned to every or
most of the system users.For example,we may want to assign some privileges to all
authenticated users.It poses a lot of maintenance trouble if we explicitly specify and
store these role assignments.We can exploit default roles to solve this problem.
A default role is a role that is implicitly assigned to every user,including both au-
thenticated and guest.We do not need to explicitly assign it to a user.When CWe-
bUser::checkAccess is invoked,default roles will be checked rst as if they are assigned to
the user.
Default roles must be declared in the CAuthManager::defaultRoles property.For example,
the following conguration declares two roles to be default roles:authenticated and guest.
return array(
'components'=>array(
'authManager'=>array(
'class'=>'CDbAuthManager',
'defaultRoles'=>array('authenticated','guest'),
),
),
);
Because a default role is assigned to every user,it usually needs to be associated with a
business rule that determines whether the role really applies to the user.For example,
the following code denes two roles,authenticated and guest,which eectively apply to
authenticated users and guest users,respectively.
160 8.Special Topics
$bizRule='return!Yii::app()->user->isGuest;';
$auth->createRole('authenticated','authenticated user',$bizRule);
$bizRule='return Yii::app()->user->isGuest;';
$auth->createRole('guest','guest user',$bizRule);
8.4 Theming
Theming is a systematic way of customizing the outlook of pages in a Web application.
By applying a new theme,the overall appearance of a Web application can be changed
instantly and dramatically.
In Yii,each theme is represented as a directory consisting of view les,layout les,and
relevant resource les such as images,CSS les,JavaScript les,etc.The name of a theme
is its directory name.All themes reside under the same directory WebRoot/themes.At any
time,only one theme can be active.
Tip:The default theme root directory WebRoot/themes can be congured to be
a dierent one.Simply congure the basePath and the baseUrl properties of the
themeManager application component to be the desired ones.
To activate a theme,set the theme property of the Web application to be the name of the
desired theme.This can be done either in the application conguration or during runtime
in controller actions.
Note:Theme name is case-sensitive.If you attempt to activate a theme that does
not exist,Yii::app()->theme will return null.
Contents under a theme directory should be organized in the same way as those under
the application base path.For example,all view les must be located under views,layout
view les under views/layouts,and system view les under views/system.For example,if
we want to replace the create view of PostController with a view in the classic theme,
we should save the new view le as WebRoot/themes/classic/views/post/create.php.
For views belonging to controllers in a module,the corresponding themed view les
should also be placed under the views directory.For example,if the aforementioned
PostController is in a module named forum,we should save the create view le as
WebRoot/themes/classic/views/forum/post/create.php.If the forum module is nested in
another module named support,then the view le should be WebRoot/themes/classic/
views/support/forum/post/create.php.
8.4 Theming 161
Note:Because the views directory may contain security-sensitive data,it should
be congured to prevent from being accessed by Web users.
When we call render or renderPartial to display a view,the corresponding view le as well
as the layout le will be looked for in the currently active theme.And if found,those les
will be rendered.Otherwise,it falls back to the default location as specied by viewPath
and layoutPath.
Tip:Inside a theme view,we often need to link other theme resource les.For
example,we may want to show an image le under the theme's images directory.
Using the baseUrl property of the currently active theme,we can generate the URL
for the image as follows,
Yii::app()->theme->baseUrl.'/images/FileName.gif'
Below is an example of directory organization for an application with two themes basic
and fancy.
WebRoot/
assets
protected/
.htaccess
components/
controllers/
models/
views/
layouts/
main.php
site/
index.php
themes/
basic/
views/
.htaccess
layouts/
main.php
site/
index.php
fancy/
views/
.htaccess
layouts/
main.php
162 8.Special Topics
site/
index.php
In the application conguration,if we congure
return array(
'theme'=>'basic',
......
);
then the basic theme will be in eect,which means the application's layout will use the
one under the directory themes/basic/views/layouts,and the site's index view will use
the one under themes/basic/views/site.In case a view le is not found in the theme,it
will fall back to the one under the protected/views directory.
8.4.1 Customizing Widgets Globally
Note:this feature has been available since version 1.1.3.
When using a widget provided by third party or Yii,we often need to customize it for spe-
cic needs.For example,we may want to change the value of CLinkPager::maxButtonCount
from 10 (default) to 5.We can accomplish this by passing the initial property values when
calling CBaseController::widget to create a widget.However,it becomes troublesome to
do so if we have to repeat the same customization in every place we use CLinkPager.
$this->widget('CLinkPager',array(
'pages'=>$pagination,
'maxButtonCount'=>5,
'cssFile'=>false,
));
Using the global widget customization feature,we only need to specify these initial values
in a single place,i.e.,the application conguration.This makes the customization of
widgets more manageable.
To use the global widget customization feature,we need to congure the widgetFactory
as follows:
return array(
'components'=>array(
8.4 Theming 163
'widgetFactory'=>array(
'widgets'=>array(
'CLinkPager'=>array(
'maxButtonCount'=>5,
'cssFile'=>false,
),
'CJuiDatePicker'=>array(
'language'=>'ru',
),
),
),
),
);
In the above,we specify the global widget customization for both CLinkPager and CJui-
DatePicker widgets by conguring the CWidgetFactory::widgets property.Note that the
global customization for each widget is represented as a key-value pair in the array,where
the key refers to the wiget class name while the value species the initial property value
array.
Now,whenever we create a CLinkPager widget in a view,the above property values will
be assigned to the widget,and we only need to write the following code in the view to
create the widget:
$this->widget('CLinkPager',array(
'pages'=>$pagination,
));
We can still override the initial property values when necessary.For example,if in some
view we want to set maxButtonCount to be 2,we can do the following:
$this->widget('CLinkPager',array(
'pages'=>$pagination,
'maxButtonCount'=>2,
));
8.4.2 Skin
Note:The skin feature has been available since version 1.1.0.
While using a theme we can quickly change the outlook of views,we can use skins to
systematically customize the outlook of the widgets used in the views.
164 8.Special Topics
A skin is an array of name-value pairs that can be used to initialize the properties of
a widget.A skin belongs to a widget class,and a widget class can have multiple skins
identied by their names.For example,we can have a skin for the CLinkPager widget
and the skin is named as classic.
In order to use the skin feature,we rst need to modify the application conguration by
conguring the CWidgetFactory::enableSkin property to be true for the widgetFactory
application component:
return array(
'components'=>array(
'widgetFactory'=>array(
'enableSkin'=>true,
),
),
);
Please note that in versions prior to 1.1.3,you need to use the following conguration to
enable widget skinning:
return array(
'components'=>array(
'widgetFactory'=>array(
'class'=>'CWidgetFactory',
),
),
);
We then create the needed skins.Skins belonging to the same widget class are stored in a
single PHP script le whose name is the widget class name.All these skin les are stored
under protected/views/skins,by default.If you want to change this to be a dierent
directory,you may congure the skinPath property of the widgetFactory component.As
an example,we may create under protected/views/skins a le named CLinkPager.php
whose content is as follows,
<?php
return array(
'default'=>array(
'nextPageLabel'=>'
0
;
'prevPageLabel'=>'',
),
'classic'=>array(
'header'=>'',
8.4 Theming 165
'maxButtonCount'=>5,
),
);
In the above,we create two skins for the CLinkPager widget:default and classic.The
former is the skin that will be applied to any CLinkPager widget that we do not explicitly
specify its skin property,while the latter is the skin to be applied to a CLinkPager widget
whose skin property is specied as classic.For example,in the following view code,the
rst pager will use the default skin while the second the classic skin:
<?php $this->widget('CLinkPager');?>
<?php $this->widget('CLinkPager',array('skin'=>'classic'));?>
If we create a widget with a set of initial property values,they will take precedence
and be merged with any applicable skin.For example,the following view code will
create a pager whose initial values will be array('header'=>'','maxButtonCount'=>6,
'cssFile'=>false),which is the result of merging the initial property values specied in
the view and the classic skin.
<?php $this->widget('CLinkPager',array(
'skin'=>'classic',
'maxButtonCount'=>6,
'cssFile'=>false,
));?>
Note that the skin feature does NOT require using themes.However,when a theme is
active,Yii will also look for skins under the skins directory of the theme's view directory
(e.g.WebRoot/themes/classic/views/skins).In case a skin with the same name exists
in both the theme and the main application view directories,the theme skin will take
precedence.
If a widget is using a skin that does not exist,Yii will still create the widget as usual
without any error.
Info:Using skin may degrade the performance because Yii needs to look for the
skin le the rst time a widget is being created.
Skin is very similar to the global widget customization feature.The main dierences are
as follows.
166 8.Special Topics
Skin is more related with the customization of presentational property values;
A widget can have multiple skins;
Skin is themeable;
Using skin is more expensive than using global widget customization.
8.5 Logging
Yii provides aexible and extensible logging feature.Messages logged can be classied
according to log levels and message categories.Using level and category lters,selected
messages can be further routed to dierent destinations,such as les,emails,browser
windows,etc.
8.5.1 Message Logging
Messages can be logged by calling either Yii::log or Yii::trace.The dierence between
these two methods is that the latter logs a message only when the application is in debug
mode.
Yii::log($message,$level,$category);
Yii::trace($message,$category);
When logging a message,we need to specify its category and level.Category is a string in
the format of xxx.yyy.zzz which resembles to the path alias.For example,if a message is
logged in CController,we may use the category system.web.CController.Message level
should be one of the following values:
trace:this is the level used by Yii::trace.It is for tracing the executionow of the
application during development.
info:this is for logging general information.
profile:this is for performance prole which is to be described shortly.
warning:this is for warning messages.
error:this is for fatal error messages.
8.5 Logging 167
8.5.2 Message Routing
Messages logged using Yii::log or Yii::trace are kept in memory.We usually need to display
them in browser windows,or save them in some persistent storage such as les,emails.
This is called message routing,i.e.,sending messages to dierent destinations.
In Yii,message routing is managed by a CLogRouter application component.It manages a
set of the so-called log routes.Each log route represents a single log destination.Messages
sent along a log route can be ltered according to their levels and categories.
To use message routing,we need to install and preload a CLogRouter application compo-
nent.We also need to congure its routes property with the log routes that we want.The
following shows an example of the needed application conguration:
array(
......
'preload'=>array('log'),
'components'=>array(
......
'log'=>array(
'class'=>'CLogRouter',
'routes'=>array(
array(
'class'=>'CFileLogRoute',
'levels'=>'trace,info',
'categories'=>'system.*',
),
array(
'class'=>'CEmailLogRoute',
'levels'=>'error,warning',
'emails'=>'admin@example.com',
),
),
),
),
)
In the above example,we have two log routes.The rst route is CFileLogRoute which
saves messages in a le under the application runtime directory.Only messages whose
level is trace or info and whose category starts with system.are saved.The second route
is CEmailLogRoute which sends messages to the specied email addresses.Only messages
whose level is error or warning are sent.
The following log routes are available in Yii:
168 8.Special Topics
CDbLogRoute:saves messages in a database table.
CEmailLogRoute:sends messages to specied email addresses.
CFileLogRoute:saves messages in a le under the application runtime directory.
CWebLogRoute:displays messages at the end of the current Web page.
CProleLogRoute:displays proling messages at the end of the current Web page.
Info:Message routing occurs at the end of the current request cycle when the
onEndRequest event is raised.To explicitly terminate the processing of the current
request,call CApplication::end() instead of die() or exit(),because CApplica-
tion::end() will raise the onEndRequest event so that the messages can be properly
logged.
Message Filtering
As we mentioned,messages can be ltered according to their levels and categories before
they are sent long a log route.This is done by setting the levels and categories properties
of the corresponding log route.Multiple levels or categories should be concatenated by
commas.
Because message categories are in the format of xxx.yyy.zzz,we may treat them as a
category hierarchy.In particular,we say xxx is the parent of xxx.yyy which is the parent
of xxx.yyy.zzz.We can then use xxx.* to represent category xxx and all its child and
grandchild categories.
Logging Context Information
Starting from version 1.0.6,we can specify to log additional context information,such
as PHP predened variables (e.g.$
GET,$
SERVER),session ID,user name,etc.This is
accomplished by specifying the CLogRoute::lter property of a log route to be a suitable
log lter.
The framework comes with the convenient CLogFilter that may be used as the needed log
lter in most cases.By default,CLogFilter will log a message with variables like $
GET,
$
SERVER which often contains valuable system context information.CLogFilter can also
be congured to prex each logged message with session ID,username,etc.,which may
greatly simplifying the global search when we are checking the numerous logged messages.
8.5 Logging 169
The following conguration shows how to enable logging context information.Note that
each log route may have its own log lter.And by default,a log route does not have a log
lter.
array(
......
'preload'=>array('log'),
'components'=>array(
......
'log'=>array(
'class'=>'CLogRouter',
'routes'=>array(
array(
'class'=>'CFileLogRoute',
'levels'=>'error',
'filter'=>'CLogFilter',
),
...other log routes...
),
),
),
)
Starting from version 1.0.7,Yii supports logging call stack information in the messages
that are logged by calling Yii::trace.This feature is disabled by default because it lowers
performance.To use this feature,simply dene a constant named YII
TRACE
LEVEL at the
beginning of the entry script (before including yii.php) to be an integer greater than 0.
Yii will then append to every trace message with the le name and line number of the call
stacks belonging to application code.The number YII
TRACE
LEVEL determines how many
layers of each call stack should be recorded.This information is particularly useful during
development stage as it can help us identify the places that trigger the trace messages.
8.5.3 Performance Proling
Performance proling is a special type of message logging.Performance proling can be
used to measure the time needed for the specied code blocks and nd out what the
performance bottleneck is.
To use performance proling,we need to identify which code blocks need to be proled.
We mark the beginning and the end of each code block by inserting the following methods:
Yii::beginProfile('blockID');
...code block being profiled...
Yii::endProfile('blockID');
170 8.Special Topics
where blockID is an ID that uniquely identies the code block.
Note,code blocks need to be nested properly.That is,a code block cannot intersect with
another.It must be either at a parallel level or be completely enclosed by the other code
block.
To show proling result,we need to install a CLogRouter application component with
a CProleLogRoute log route.This is the same as we do with normal message routing.
The CProleLogRoute route will display the performance results at the end of the current
page.
Proling SQL Executions
Proling is especially useful when working with database since SQL executions are of-
ten the main performance bottleneck of an application.While we can manually insert
beginProfile and endProfile statements at appropriate places to measure the time spent
in each SQL execution,starting from version 1.0.6,Yii provides a more systematic ap-
proach to solve this problem.
By setting CDbConnection::enableProling to be true in the application conguration,
every SQL statement being executed will be proled.The results can be readily displayed
using the aforementioned CProleLogRoute,which can show us how much time is spent
in executing what SQL statement.We can also call CDbConnection::getStats() to retrieve
the total number SQL statements executed and their total execution time.
8.6 Error Handling
Yii provides a complete error handling framework based on the PHP 5 exception mecha-
nism.When the application is created to handle an incoming user request,it registers its
handleError method to handle PHP warnings and notices;and it registers its handleExcep-
tion method to handle uncaught PHP exceptions.Consequently,if a PHP warning/notice
or an uncaught exception occurs during the application execution,one of the error handlers
will take over the control and start the necessary error handling procedure.
Tip:The registration of error handlers is done in the application's constructor by
calling PHP functions set
exception
handler and set
error
handler.If you do not
want Yii to handle the errors and exceptions,you may dene constant YII
ENABLE
ERROR
HANDLER and YII
ENABLE
EXCEPTION
HANDLER to be false in the entry script.
8.6 Error Handling 171
By default,errorHandler (or exceptionHandler) will raise an onError event (or onException
event).If the error (or exception) is not handled by any event handler,it will call for help
from the errorHandler application component.
8.6.1 Raising Exceptions
Raising exceptions in Yii is not dierent from raising a normal PHP exception.One uses
the following syntax to raise an exception when needed:
throw new ExceptionClass('ExceptionMessage');
Yii denes two exception classes:CException and CHttpException.The former is a
generic exception class,while the latter represents an exception that should be displayed
to end users.The latter also carries a statusCode property representing an HTTP status
code.The class of an exception determines how it should be displayed,as we will explain
next.
Tip:Raising a CHttpException exception is a simple way of reporting errors caused
by user misoperation.For example,if the user provides an invalid post ID in the
URL,we can simply do the following to show a 404 error (page not found):
//if post ID is invalid
throw new CHttpException(404,'The specified post cannot be found.');
8.6.2 Displaying Errors
When an error is forwarded to the CErrorHandler application component,it chooses an
appropriate view to display the error.If the error is meant to be displayed to end users,
such as a CHttpException,it will use a view named errorXXX,where XXX stands for the
HTTP status code (e.g.400,404,500).If the error is an internal one and should only be
displayed to developers,it will use a view named exception.In the latter case,complete
call stack as well as the error line information will be displayed.
Info:When the application runs in production mode,all errors including those
internal ones will be displayed using view errorXXX.This is because the call stack
of an error may contain sensitive information.In this case,developers should rely
on the error logs to determine what is the real cause of an error.
CErrorHandler searches for the view le corresponding to a view in the following order:
172 8.Special Topics
1.WebRoot/themes/ThemeName/views/system:this is the system view directory under the
currently active theme.
2.WebRoot/protected/views/system:this is the default system view directory for an
application.
3.yii/framework/views:this is the standard systemview directory provided by the Yii
framework.
Therefore,if we want to customize the error display,we can simply create error view les
under the system view directory of our application or theme.Each view le is a normal
PHP script consisting of mainly HTML code.For more details,please refer to the default
view les under the framework's view directory.
Handling Errors Using an Action
Starting from version 1.0.6,Yii allows using a controller action to handle the error display
work.To do so,we should congure the error handler in the application conguration as
follows:
return array(
......
'components'=>array(
'errorHandler'=>array(
'errorAction'=>'site/error',
),
),
);
In the above,we congure the CErrorHandler::errorAction property to be the route site/
error which refers to the error action in SiteController.We may use a dierent route if
needed.
We can write the error action like the following:
public function actionError()
f
if($error=Yii::app()->errorHandler->error)
$this->render('error',$error);
g
8.7 Web Service 173
In the action,we rst retrieve the detailed error information from CErrorHandler::error.
If it is not empty,we render the error view together with the error information.The error
information returned from CErrorHandler::error is an array with the following elds:
code:the HTTP status code (e.g.403,500);
type:the error type (e.g.CHttpException,PHP Error);
message:the error message;
file:the name of the PHP script le where the error occurs;
line:the line number of the code where the error occurs;
trace:the call stack of the error;
source:the context source code where the error occurs.
Tip:The reason we check if CErrorHandler::error is empty or not is because the
error action may be directly requested by an end user,in which case there is no
error.Since we are passing the $error array to the view,it will be automatically
expanded to individual variables.As a result,in the view we can access directly the
variables such as $code,$type.
8.6.3 Message Logging
A message of level error will always be logged when an error occurs.If the error is caused
by a PHP warning or notice,the message will be logged with category php;if the error is
caused by an uncaught exception,the category would be exception.ExceptionClassName
(for CHttpException its statusCode will also be appended to the category).One can thus
exploit the logging feature to monitor errors happened during application execution.
8.7 Web Service
Web service is a software system designed to support interoperable machine-to-machine
interaction over a network.In the context of Web applications,it usually refers to a set of
APIs that can be accessed over the Internet and executed on a remote system hosting the
requested service.For example,a Flex-based client may invoke a function implemented
on the server side running a PHP-based Web application.Web service relies on SOAP as
its foundation layer of the communication protocol stack.
174 8.Special Topics
Yii provides CWebService and CWebServiceAction to simplify the work of implementing
Web service in a Web application.The APIs are grouped into classes,called service
providers.Yii will generate for each class a WSDL specication which describes what
APIs are available and how they should be invoked by client.When an API is invoked by
a client,Yii will instantiate the corresponding service provider and call the requested API
to fulll the request.
Note:CWebService relies on the PHP SOAP extension.Make sure you have
enabled it before trying the examples displayed in this section.
8.7.1 Dening Service Provider
As we mentioned above,a service provider is a class dening the methods that can be
remotely invoked.Yii relies on doc comment and class reection to identify which methods
can be remotely invoked and what are their parameters and return value.
Let's start with a simple stock quoting service.This service allows a client to request for
the quote of the specied stock.We dene the service provider as follows.Note that we
dene the provider class StockController by extending CController.This is not required.
We will explain why we do so shortly.
class StockController extends CController
f
/**
* @param string the symbol of the stock
* @return float the stock price
* @soap
*/
public function getPrice($symbol)
f
$prices=array('IBM'=>100,'GOOGLE'=>350);
return isset($prices[$symbol])?$prices[$symbol]:0;
//...return stock price for $symbol
g
g
In the above,we declare the method getPrice to be a Web service API by marking it with
the tag @soap in its doc comment.We rely on doc comment to specify the data type of
the input parameters and return value.Additional APIs can be declared in the similar
way.
8.7 Web Service 175
8.7.2 Declaring Web Service Action
Having dened the service provider,we need to make it available to clients.In particular,
we want to create a controller action to expose the service.This can be done easily by
declaring a CWebServiceAction action in a controller class.For our example,we will just
put it in StockController.
class StockController extends CController
f
public function actions()
f
return array(
'quote'=>array(
'class'=>'CWebServiceAction',
),
);
g
/**
* @param string the symbol of the stock
* @return float the stock price
* @soap
*/
public function getPrice($symbol)
f
//...return stock price for $symbol
g
g
That is all we need to create a Web service!If we try to access the action by URL http:
//hostname/path/to/index.php?r=stock/quote,we will see a lot of XML content which is
actually the WSDL for the Web service we dened.
Tip:By default,CWebServiceAction assumes the current controller is the service
provider.That is why we dene the getPrice method inside the StockController
class.
8.7.3 Consuming Web Service
To complete the example,let's create a client to consume the Web service we just created.
The example client is written in PHP,but it could be in other languages,such as Java,
C#,Flex,etc.
$client=new SoapClient('http://hostname/path/to/index.php?r=stock/quote');
176 8.Special Topics
echo $client->getPrice('GOOGLE');
Run the above script in either Web or console mode,and we shall see 350 which is the
price for GOOGLE.
8.7.4 Data Types
When declaring class methods and properties to be remotely accessible,we need to specify
the data types of the input and output parameters.The following primitive data types
can be used:
str/string:maps to xsd:string;
int/integer:maps to xsd:int;
oat/double:maps to xsd:float;
bool/boolean:maps to xsd:boolean;
date:maps to xsd:date;
time:maps to xsd:time;
datetime:maps to xsd:dateTime;
array:maps to xsd:string;
object:maps to xsd:struct;
mixed:maps to xsd:anyType.
If a type is not any of the above primitive types,it is considered as a composite type
consisting of properties.A composite type is represented in terms of a class,and its
properties are the class'public member variables marked with @soap in their doc comments.
We can also use array type by appending [] to the end of a primitive or composite type.
This would specify an array of the specied type.
Belowis an example dening the getPosts Web API which returns an array of Post objects.
class PostController extends CController
f
/**
* @return Post[] a list of posts
8.7 Web Service 177
* @soap
*/
public function getPosts()
f
return Post::model()->findAll();
g
g
class Post extends CActiveRecord
f
/**
* @var integer post ID
* @soap
*/
public $id;
/**
* @var string post title
* @soap
*/
public $title;
public static function model($className=
CLASS
)
f
return parent::model($className);
g
g
8.7.5 Class Mapping
In order to receive parameters of composite type from client,an application needs to
declare the mapping from WSDL types to the corresponding PHP classes.This is done
by conguring the classMap property of CWebServiceAction.
class PostController extends CController
f
public function actions()
f
return array(
'service'=>array(
'class'=>'CWebServiceAction',
'classMap'=>array(
'Post'=>'Post',//or simply'Post'
),
),
);
g
......
g
178 8.Special Topics
8.7.6 Intercepting Remote Method Invocation
By implementing the IWebServiceProvider interface,a sevice provider can intercept re-
mote method invocations.In IWebServiceProvider::beforeWebMethod,the provider may
retrieve the current CWebService instance and obtain the the name of the method cur-
rently being requested via CWebService::methodName.It can return false if the remote
method should not be invoked for some reason (e.g.unauthorized access).
8.8 Internationalization
Internationalization (I18N) refers to the process of designing a software application so
that it can be adapted to various languages and regions without engineering changes.For
Web applications,this is of particular importance because the potential users may be from
worldwide.
Yii provides support for I18N in several aspects.
It provides the locale data for each possible language and variant.
It provides message and le translation service.
It provides locale-dependent date and time formatting.
It provides locale-dependent number formatting.
In the following subsections,we will elaborate each of the above aspects.
8.8.1 Locale and Language
Locale is a set of parameters that denes the user's language,country and any special
variant preferences that the user wants to see in their user interface.It is usually identied
by an ID consisting of a language ID and a region ID.For example,the ID en
US stands
for the locale of English and United States.For consistency,all locale IDs in Yii are
canonicalized to the format of LanguageID or LanguageID
RegionID in lower case (e.g.en,
en
us).
Locale data is represented as a CLocale instance.It provides locale-dependent information,
including currency symbols,number symbols,currency formats,number formats,date and
time formats,and date-related names.Since the language information is already implied in
the locale ID,it is not provided by CLocale.For the same reason,we often interchangeably
using the term locale and language.
8.8 Internationalization 179
Given a locale ID,one can get the corresponding CLocale instance by CLocale::getInstance($localeID)
or CApplication::getLocale($localeID).
Info:Yii comes with locale data for nearly every language and region.The data
is obtained from Common Locale Data Repository (CLDR).For each locale,only a
subset of the CLDR data is provided as the original data contains a lot of rarely used
information.Starting fromversion 1.1.0,users can also supply their own customized
locale data.To do so,congure the CApplication::localeDataPath property with the
directory that contains the customized locale data.Please refer to the locale data
les under framework/i18n/data in order to create customized locale data les.
For a Yii application,we dierentiate its target language fromsource language.The target
language is the language (locale) of the users that the application is targeted at,while the
source language refers to the language (locale) that the application source les are written
in.Internationalization occurs only when the two languages are dierent.
One can congure target language in the application conguration,or change it dynami-
cally before any internationalization occurs.
Tip:Sometimes,we may want to set the target language as the language preferred
by a user (specied in user's browser preference).To do so,we can retrieve the user
preferred language ID using CHttpRequest::preferredLanguage.
8.8.2 Translation
The most needed I18N feature is perhaps translation,including message translation and
view translation.The former translates a text message to the desired language,while the
latter translates a whole le to the desired language.
A translation request consists of the object to be translated,the source language that the
object is in,and the target language that the object needs to be translated to.In Yii,the
source language is default to the application source language while the target language
is default to the application language.If the source and target languages are the same,
translation will not occur.
Message Translation
Message translation is done by calling Yii::t().The method translates the given message
from source language to target language.
180 8.Special Topics
When translating a message,its category has to be specied since a message may be
translated dierently under dierent categories (contexts).The category yii is reserved
for messages used by the Yii framework core code.
Messages can contain parameter placeholders which will be replaced with the actual pa-
rameter values when calling Yii::t().For example,the following message translation re-
quest would replace the faliasg placeholder in the original message with the actual alias
value.
Yii::t('app','Path alias"faliasg"is redefined.',
array('faliasg'=>$alias))
Note:Messages to be translated must be constant strings.They should not contain
variables that would change message content (e.g."Invalid f$messageg content.
").Use parameter placeholders if a message needs to vary according to some pa-
rameters.
Translated messages are stored in a repository called message source.A message source is
represented as an instance of CMessageSource or its child class.When Yii::t() is invoked,
it will look for the message in the message source and return its translated version if it is
found.
Yii comes with the following types of message sources.You may also extend CMessage-
Source to create your own message source type.
CPhpMessageSource:the message translations are stored as key-value pairs in a
PHP array.The original message is the key and the translated message is the value.
Each array represents the translations for a particular category of messages and is
stored in a separate PHP script le whose name is the category name.The PHP
translation les for the same language are stored under the same directory named
as the locale ID.And all these directories are located under the directory specied
by basePath.
CGettextMessageSource:the message translations are stored as GNU Gettext les.
CDbMessageSource:the message translations are stored in database tables.For
more details,see the API documentation for CDbMessageSource.
A message source is loaded as an application component.Yii pre-declares an application
component named messages to store messages that are used in user application.By default,
8.8 Internationalization 181
the type of this message source is CPhpMessageSource and the base path for storing the
PHP translation les is protected/messages.
In summary,in order to use message translation,the following steps are needed:
1.Call Yii::t() at appropriate places;
2.Create PHPtranslation les as protected/messages/LocaleID/CategoryName.php.Each
le simply returns an array of message translations.Note,this assumes you are using
the default CPhpMessageSource to store the translated messages.
3.Congure CApplication::sourceLanguage and CApplication::language.
Tip:The yiic tool in Yii can be used to manage message translations when CPh-
pMessageSource is used as the message source.Its message command can automat-
ically extract messages to be translated from selected source les and merge them
with existing translations if necessary.
Starting from version 1.0.10,when using CPhpMessageSource to manage message source,
messages for an extension class (e.g.a widget,a module) can be specially managed and
used.In particular,if a message belongs to an extension whose class name is Xyz,then the
message category can be specied in the format of Xyz.categoryName.The correspond-
ing message le will be assumed to be BasePath/messages/LanguageID/categoryName.php,
where BasePath refers to the directory that contains the extension class le.And when
using Yii::t() to translate an extension message,the following format should be used,
instead:
Yii::t('Xyz.categoryName','message to be translated')
Since version 1.0.2,Yii has added the support for choice format.Choice format refers to
choosing a translated according to a given number value.For example,in English the
word'book'may either take a singular form or a plural form depending on the number of
books,while in other languages,the word may not have dierent form (such as Chinese)
or may have more complex plural form rules (such as Russian).Choice format solves this
problem in a simple yet eective way.
To use choice format,a translated message must consist of a sequence of expression-
message pairs separated by |,as shown below:
'expr1#message1|expr2#message2|expr3#message3'
182 8.Special Topics
where exprN refers to a valid PHP expression which evaluates to a boolean value indicating
whether the corresponding message should be returned.Only the message corresponding
to the rst expression that evaluates to true will be returned.An expression can contain
a special variable named n (note,it is not $n) which will take the number value passed as
the rst message parameter.For example,assuming a translated message is:
'n==1#one book|n>1#many books'
and we are passing a number value 2 in the message parameter array when calling Yii::t(),
we would obtain many books as the nal translated message.
As a shortcut notation,if an expression is a number,it will be treated as n==Number.
Therefore,the above translated message can be also be written as:
'1#one book|n>1#many books'
File Translation
File translation is accomplished by calling CApplication::ndLocalizedFile().Given the
path of a le to be translated,the method will look for a le with the same name under
the LocaleID subdirectory.If found,the le path will be returned;otherwise,the original
le path will be returned.
File translation is mainly used when rendering a view.When calling one of the render
methods in a controller or widget,the view les will be translated automatically.For
example,if the target language is zh
cn while the source language is en
us,rendering a view
named edit would resulting in searching for the view le protected/views/ControllerID/
zh
cn/edit.php.If the le is found,this translated version will be used for rendering;
otherwise,the le protected/views/ControllerID/edit.php will be rendered instead.
File translation may also be used for other purposes,for example,displaying a translated
image or loading a locale-dependent data le.
8.8.3 Date and Time Formatting
Date and time are often in dierent formats in dierent countries or regions.The task of
date and time formatting is thus to generate a date or time string that ts for the specied
locale.Yii provides CDateFormatter for this purpose.
Each CDateFormatter instance is associated with a target locale.To get the format-
ter associated with the target locale of the whole application,we can simply access the
8.9 Using Alternative Template Syntax 183
dateFormatter property of the application.
The CDateFormatter class mainly provides two methods to format a UNIX timestamp.
format:this method formats the given UNIX timestamp into a string according to
a customized pattern (e.g.$dateFormatter->format('yyyy-MM-dd',$timestamp)).
formatDateTime:this method formats the given UNIX timestamp into a string
according to a pattern predened in the target locale data (e.g.short format of
date,long format of time).
8.8.4 Number Formatting
Like data and time,numbers may also be formatted dierently in dierent countries
or regions.Number formatting includes decimal formatting,currency formatting and
percentage formatting.Yii provides CNumberFormatter for these tasks.
To get the number formatter associated with the target locale of the whole application,
we can access the numberFormatter property of the application.
The following methods are provided by CNumberFormatter to format an integer or double
value.
format:this method formats the given number into a string according to a cus-
tomized pattern (e.g.$numberFormatter->format('#,##0.00',$number)).
formatDecimal:this method formats the given number using the decimal pattern
predened in the target locale data.
formatCurrency:this method formats the given number and currency code using
the currency pattern predened in the target locale data.
formatPercentage:this method formats the given number using the percentage pat-
tern predened in the target locale data.
8.9 Using Alternative Template Syntax
Yii allows developers to use their own favorite template syntax (e.g.Prado,Smarty) to
write controller or widget views.This is achieved by writing and installing a viewRen-
derer application component.The view renderer intercepts the invocations of CBaseCon-
troller::renderFile,compiles the view le with customized template syntax,and renders
the compiling results.
184 8.Special Topics
Info:It is recommended to use customized template syntax only when writing views
that are less likely to be reused.Otherwise,people who are reusing the views would
be forced to use the same customized template syntax in their applications.
In the following,we introduce how to use CPradoViewRenderer,a view renderer that
allows developers to use the template syntax similar to that in Prado framework.For
people who want to develop their own view renderers,CPradoViewRenderer is a good
reference.
8.9.1 Using CPradoViewRenderer
To use CPradoViewRenderer,we just need to congure the application as follows:
return array(
'components'=>array(
......,
'viewRenderer'=>array(
'class'=>'CPradoViewRenderer',
),
),
);
By default,CPradoViewRenderer will compile source view les and save the resulting
PHP les under the runtime directory.Only when the source view les are changed,will
the PHP les be re-generated.Therefore,using CPradoViewRenderer incurs very little
performance degradation.
Tip:While CPradoViewRenderer mainly introduces some new template tags to
make writing views easier and faster,you can still write PHP code as usual in the
source views.
In the following,we introduce the template tags that are supported by CPradoViewRen-
derer.
Short PHP Tags
Short PHP tags are shortcuts to writing PHP expressions and statements in a view.The
expression tag <%= expression %> is translated into <?php echo expression?>;while the
statement tag <% statement %> to <?php statement?>.For example,
8.9 Using Alternative Template Syntax 185
<%= CHtml::textField($name,'value');%>
<% foreach($models as $model):%>
is translated into
<?php echo CHtml::textField($name,'value');?>
<?php foreach($models as $model):?>
Component Tags
Component tags are used to insert a widget in a view.It uses the following syntax:
<com:WidgetClass property1=value1 property2=value2...>
//body content for the widget
</com:WidgetClass>
//a widget without body content
<com:WidgetClass property1=value1 property2=value2.../>
where WidgetClass species the widget class name or class path alias,and property initial
values can be either quoted strings or PHP expressions enclosed within a pair of curly
brackets.For example,
<com:CCaptcha captchaAction="captcha"showRefreshButton=ffalseg/>
would be translated as
<?php $this->widget('CCaptcha',array(
'captchaAction'=>'captcha',
'showRefreshButton'=>false));?>
Note:The value for showRefreshButton is specied as ffalseg instead of"false"
because the latter means a string instead of a boolean.
Cache Tags
Cache tags are shortcuts to using fragment caching.Its syntax is as follows,
186 8.Special Topics
<cache:fragmentID property1=value1 property2=value2...>
//content being cached
</cache:fragmentID >
where fragmentID should be an identier that uniquely identies the content being cached,
and the property-value pairs are used to congure the fragment cache.For example,
<cache:profile duration=f3600g>
//user profile information here
</cache:profile >
would be translated as
<?php if($this->cache('profile',array('duration'=>3600))):?>
//user profile information here
<?php $this->endCache();endif;?>
Clip Tags
Like cache tags,clip tags are shortcuts to calling CBaseController::beginClip and CBaseC-
ontroller::endClip in a view.The syntax is as follows,
<clip:clipID>
//content for this clip
</clip:clipID >
where clipID is an identier that uniquely identies the clip content.The clip tags will
be translated as
<?php $this->beginClip('clipID');?>
//content for this clip
<?php $this->endClip();?>
Comment Tags
Comment tags are used to write view comments that should only be visible to developers.
Comment tags will be stripped o when the view is displayed to end users.The syntax
for comment tags is as follows,
8.10 Console Applications 187
<!---
view comments that will be stripped off
--->
8.9.2 Mixing Template Formats
Starting from version 1.1.2,it is possible to mix the usage of some alternative template
syntax with the normal PHP syntax.To do so,the CViewRenderer::leExtension property
of the installed view renderer must be congured with a value other than.php.For
example,if the property is set as.tpl,then any view le ending with.tpl will be rendered
using the installed view renderer,while all other view les ending with.php will be treated
as normal PHP view script.
8.10 Console Applications
Console applications are mainly used by a Web application to perform oine work,such
as code generation,search index compiling,email sending,etc.Yii provides a framework
for writing console applications in an object-oriented and systematic way.
Yii represents each console task in terms of a command,and a console application instance
is used to dispatch a command line request to an appropriate command.The application
instance is created in an entry script.To execute a console task,we simply run the
corresponding command on the command line as follows,
php entryScript.php CommandName Param0 Param1...
where CommandName refers to the command name which is case-insensitive,and Param0,
Param1 and so on are parameters to be passed to the command instance.
The entry script for a console application is usually written like the following,similar to
that in a Web application,
defined('YII
DEBUG') or define('YII
DEBUG',true);
//include Yii bootstrap file
require
once('path/to/yii/framework/yii.php');
//create application instance and run
$configFile='path/to/config/file.php';
Yii::createConsoleApplication($configFile)->run();
We then create command classes which should extend from CConsoleCommand.Each
command class should be named as its command name appended with Command.For
188 8.Special Topics
example,to dene an email command,we should write an EmailCommand class.All com-
mand class les should be placed under the commands subdirectory of the application base
directory.
Tip:By conguring CConsoleApplication::commandMap,one can also have com-
mand classes in dierent naming conventions and located in dierent directories.
Writing a command class mainly involves implementing the CConsoleCommand::run method.
Command line parameters are passed as an array to this method.Below is an example:
class EmailCommand extends CConsoleCommand
f
public function run($args)
f
$receiver=$args[0];
//send email to $receiver
g
g
At any time in a command,we can access the console application instance via Yii::app().
Like a Web application instance,console application can also be congured.For example,
we can congure a db application component to access the database.The conguration
is usually specied as a PHP le and passed to the constructor of the console application
class (or createConsoleApplication in the entry script).
8.10.1 Using the yiic Tool
We have used the yiic tool to create our rst application.The yiic tool is in fact
implemented as a console application whose entry script le is framework/yiic.php.Using
yiic,we can accomplish tasks such as creating a Web application skeleton,generating a
controller class or model class,generating code needed by CRUD operations,extracting
messages to be translated,etc.
We can enhance yiic by adding our own customized commands.To do so,we should
start with a skeleton application created using yiic webapp command,as described in
Creating First Yii Application.The yiic webapp command will generate two les under
the protected directory:yiic and yiic.bat.They are the local version of the yiic tool
created specically for the Web application.
We can then create our own commands under the protected/commands directory.Running
the local yiic tool,we will see our own commands appearing together with the standard
8.11 Security 189
ones.We can also create our own commands to be used in the yiic shell tool.To do so,
just drop our command class les under the protected/commands/shell directory.
Starting from version 1.1.1,we can also create global commands that can be shared by all
Yii applications on the same machine.To do so,dene an environment variable named
YII
CONSOLE
COMMANDS which should point to an existing directory.We then put our global
command class les under this directory,and we will see these commands become available
wherever we use the yiic tool.
8.11 Security
8.11.1 Cross-site Scripting Prevention
Cross-site scripting (also known as XSS) occurs when a web application gathers malicious
data from a user.Often attackers will inject JavaScript,VBScript,ActiveX,HTML,or
Flash into a vulnerable application to fool other application users and gather data from
them.For example,a poorly design forum system may display user input in forum posts
without any checking.An attacker can then inject a piece of malicious JavaScript code
into a post so that when other users read this post,the JavaScript runs unexpectedly on
their computers.
One of the most important measures to prevent XSS attacks is to check user input before
displaying them.One can do HTML-encoding with the user input to achieve this goal.
However,in some situations,HTML-encoding may not be preferable because it disables
all HTML tags.
Yii incorporates the work of HTMLPurier and provides developers with a useful compo-
nent called CHtmlPurier that encapsulates HTMLPurier.This component is capable
of removing all malicious code with a thoroughly audited,secure yet permissive whitelist
and making sure the ltered content is standard-compliant.
The CHtmlPurier component can be used as either a widget or a lter.When used as a
widget,CHtmlPurier will purify contents displayed in its body in a view.For example,
<?php $this->beginWidget('CHtmlPurifier');?>
...display user-entered content here...
<?php $this->endWidget();?>
8.11.2 Cross-site Request Forgery Prevention
Cross-Site Request Forgery (CSRF) attacks occur when a malicious web site causes a user's
web browser to perform an unwanted action on a trusted site.For example,a malicious
190 8.Special Topics
web site has a page that contains an image tag whose src points to a banking site:http:
//bank.example/withdraw?transfer=10000&to=someone.If a user who has a login cookie
for the banking site happens to visit this malicous page,the action of transferring 10000
dollars to someone will be executed.Contrary to cross-site,which exploits the trust a user
has for a particular site,CSRF exploits the trust that a site has for a particular user.
To prevent CSRF attacks,it is important to abide to the rule that GET requests should
only be allowed to retrieve data rather than modify any data on the server.And for POST
requests,they should include some random value which can be recognized by the server
to ensure the form is submitted from and the result is sent back to the same origin.
Yii implements a CSRF prevention scheme to help defeat POST-based attacks.It is based
on storing a random value in a cookie and comparing this value with the value submitted
via the POST request.
By default,the CSRF prevention is disabled.To enable it,congure the CHttpRequest
application component in the application conguration as follows,
return array(
'components'=>array(
'request'=>array(
'enableCsrfValidation'=>true,
),
),
);
And to display a form,call CHtml::form instead of writing the HTML form tag directly.
The CHtml::form method will embed the necessary random value in a hidden eld so that
it can be submitted for CSRF validation.
8.11.3 Cookie Attack Prevention
Protecting cookies from being attacked is of extreme importance,as session IDs are com-
monly stored in cookies.If one gets hold of a session ID,he essentially owns all relevant
session information.
There are several countermeasures to prevent cookies from being attacked.
An application can use SSL to create a secure communication channel and only pass
the authentication cookie over an HTTPS connection.Attackers are thus unable to
decipher the contents in the transferred cookies.
8.12 Performance Tuning 191
Expire sessions appropriately,including all cookies and session tokens,to reduce the
likelihood of being attacked.
Prevent cross-site scripting which causes arbitrary code to run in a user's browser
and expose his cookies.
Validate cookie data and detect if they are altered.
Yii implements a cookie validation scheme that prevents cookies from being modied.In
particular,it does HMAC check for the cookie values if cookie validation is enable.
Cookie validation is disabled by default.To enable it,congure the CHttpRequest appli-
cation component in the application conguration as follows,
return array(
'components'=>array(
'request'=>array(
'enableCookieValidation'=>true,
),
),
);
To make use of the cookie validation scheme provided by Yii,we also need to access cookies
through the cookies collection,instead of directly through $
COOKIES:
//retrieve the cookie with the specified name
$cookie=Yii::app()->request->cookies[$name];
$value=$cookie->value;
......
//send a cookie
$cookie=new CHttpCookie($name,$value);
Yii::app()->request->cookies[$name]=$cookie;
8.12 Performance Tuning
Performance of Web applications is aected by many factors.Database access,le system
operations,network bandwidth are all potential aecting factors.Yii has tried in every
aspect to reduce the performance impact caused by the framework.But still,there are
many places in the user application that can be improved to boost performance.
8.12.1 Enabling APC Extension
Enabling the PHP APC extension is perhaps the easiest way to improve the overall per-
formance of an application.The extension caches and optimizes PHP intermediate code
192 8.Special Topics
and avoids the time spent in parsing PHP scripts for every incoming request.
8.12.2 Disabling Debug Mode
Disabling debug mode is another easy way to improve performance.A Yii application runs
in debug mode if the constant YII
DEBUG is dened as true.Debug mode is useful during
development stage,but it would impact performance because some components cause
extra burden in debug mode.For example,the message logger may record additional
debug information for every message being logged.
8.12.3 Using yiilite.php
When the PHP APC extension is enabled,we can replace yii.php with a dierent Yii
bootstrap le named yiilite.php to further boost the performance of a Yii-powered ap-
plication.
The le yiilite.php comes with every Yii release.It is the result of merging some com-
monly used Yii class les.Both comments and trace statements are stripped from the
merged le.Therefore,using yiilite.php would reduce the number of les being included
and avoid execution of trace statements.
Note,using yiilite.php without APC may actually reduce performance,because yiilite.
php contains some classes that are not necessarily used in every request and would take
extra parsing time.It is also observed that using yiilite.php is slower with some server
congurations,even when APC is turned on.The best way to judge whether to use
yiilite.php or not is to run a benchmark using the included hello world demo.
8.12.4 Using Caching Techniques
As described in the Caching section,Yii provides several caching solutions that may im-
prove the performance of a Web application signicantly.If the generation of some data
takes long time,we can use the data caching approach to reduce the data generation fre-
quency;If a portion of page remains relatively static,we can use the fragment caching
approach to reduce its rendering frequency;If a whole page remains relative static,we can
use the page caching approach to save the rendering cost for the whole page.
If the application is using Active Record,we should turn on the schema caching to save
the time of parsing database schema.This can be done by conguring the CDbConnec-
tion::schemaCachingDuration property to be a value greater than 0.
Besides these application-level caching techniques,we can also use server-level caching
solutions to boost the application performance.As a matter of fact,the APC caching we
8.12 Performance Tuning 193
described earlier belongs to this category.There are other server techniques,such as Zend
Optimizer,eAccelerator,Squid,to name a few.
8.12.5 Database Optimization
Fetching data from database is often the main performance bottleneck in a Web applica-
tion.Although using caching may alleviate the performance hit,it does not fully solve
the problem.When the database contains enormous data and the cached data is invalid,
fetching the latest data could be prohibitively expensive without proper database and
query design.
Design index wisely in a database.Indexing can make SELECT queries much faster,but it
may slow down INSERT,UPDATE or DELETE queries.
For complex queries,it is recommended to create a database view for it instead of issuing
the queries inside the PHP code and asking DBMS to parse them repetitively.
Do not overuse Active Record.Although Active Record is good at modelling data in an
OOP fashion,it actually degrades performance due to the fact that it needs to create one
or several objects to represent each row of query result.For data intensive applications,
using DAO or database APIs at lower level could be a better choice.
Last but not least,use LIMIT in your SELECT queries.This avoids fetching overwhelming
data from database and exhausting the memory allocated to PHP.
8.12.6 Minimizing Script Files
Complex pages often need to include many external JavaScript and CSS les.Because
each le would cause one extra round trip to the server and back,we should minimize the
number of script les by merging them into fewer ones.We should also consider reducing
the size of each script le to reduce the network transmission time.There are many tools
around to help on these two aspects.
For a page generated by Yii,chances are that some script les are rendered by components
that we do not want to modify (e.g.Yii core components,third-party components).In
order to minimizing these script les,we need two steps.
Note:The scriptMap feature described in the following has been available since
version 1.0.3.
First,we declare the scripts to be minimized by conguring the scriptMap property of the
194 8.Special Topics
clientScript application component.This can be done either in the application congura-
tion or in code.For example,
$cs=Yii::app()->clientScript;
$cs->scriptMap=array(
'jquery.js'=>'/js/all.js',
'jquery.ajaxqueue.js'=>'/js/all.js',
'jquery.metadata.js'=>'/js/all.js',
......
);
What the above code does is that it maps those JavaScript les to the URL/js/all.js.
If any of these JavaScript les need to be included by some components,Yii will include
the URL (once) instead of the individual script les.
Second,we need to use some tools to merge (and perhaps compress) the JavaScript les
into a single one and save it as js/all.js.
The same trick also applies to CSS les.
We can also improve page loading speed with the help of Google AJAX Libraries API.
For example,we can include jquery.js from Google servers instead of our own server.To
do so,we rst congure the scriptMap as follows,
$cs=Yii::app()->clientScript;
$cs->scriptMap=array(
'jquery.js'=>false,
'jquery.ajaxqueue.js'=>false,
'jquery.metadata.js'=>false,
......
);
By mapping these script les to false,we prevent Yii from generating the code to include
these les.Instead,we write the following code in our pages to explicitly include the script
les from Google,
<head>
<?php echo CGoogleApi::init();?>
<?php echo CHtml::script(
CGoogleApi::load('jquery','1.3.2')."nn".
CGoogleApi::load('jquery.ajaxqueue.js')."nn".
CGoogleApi::load('jquery.metadata.js')
);?>
8.13 Code Generation using Command Line Tools (deprecated) 195
......
</head>
8.13 Code Generation using Command Line Tools (depre-
cated)
Note:The code generators in yiic shell have been deprecated since version 1.1.2.
Please use the more powerful and extensible Web-based code generators available
in Gii,instead.
Open a command line window,and execute the commands listed as follows,
% cd WebRoot/testdrive
% protected/yiic shell
Yii Interactive Tool v1.1
Please type'help'for help.Type'exit'to quit.
>> model User tbl_user
generate models/User.php
generate fixtures/tbl_user.php
generate unit/UserTest.php
The following model classes are successfully generated:
User
If you have a'db'database connection,you can test these models now with:
$model=User::model()->find();
print_r($model);
>> crud User
generate UserController.php
generate UserTest.php
mkdir D:/testdrive/protected/views/user
generate create.php
generate update.php
generate index.php
generate view.php
generate admin.php
generate _form.php
generate _view.php
Crud'user'has been successfully created.You may access it via:
http://hostname/path/to/index.php?r=user
In the above,we use the yiic shell command to interact with our skeleton application.
At the prompt,we execute two sub-commands:model User tbl
user and crud User.The
196 8.Special Topics
former generates a model class named User for the tbl
user table,while the latter analyzes
the User model and generates the code implementing the corresponding CRUD operations.
Note:You may encounter errors like"...could not nd driver",even though the
requirement checker shows you have already enabled PDO and the corresponding
PDO driver.If this happens,you may try to run the yiic tool as follows,
% php -c path/to/php.ini protected/yiic.php shell
where path/to/php.ini represents the correct PHP ini le.
Let's enjoy our work by browsing the following URL:
http://hostname/testdrive/index.php?r=user
This will display a list of user entries in the tbl
user table.
Click the Create User button on the page.We will be brought to the login page if we have
not logged in before.After logged in,we see an input form that allows us to add a new
user entry.Complete the form and click on the Create button.If there is any input error,
a nice error prompt will show up which prevents us from saving the input.Back to the
user list page,we should see the newly added user appearing in the list.
Repeat the above steps to add more users.Notice that user list page will automatically
paginate the user entries if there are too many to be displayed in one page.
If we login as an administrator using admin/admin,we can view the user admin page with
the following URL:
http://hostname/testdrive/index.php?r=user/admin
This will show us the user entries in a nice tabular format.We can click on the table
header cells to sort the corresponding columns.We can click on the buttons on each row
of data to view,update or delete the corresponding row of data.We can browse dierent
pages.We can also lter and search to look for the data we are interested in.
All these nice features come without requiring us to write a single line of code!
8.13 Code Generation using Command Line Tools (deprecated) 197
Figure 8.1:User admin page
198 8.Special Topics
Figure 8.2:Create new user page